So I found this post quite interesting:

http://www.gnxp.com/blog/2009/03/gnxp-readers-do-not-breed.php

(I'm quite sure that the demographics of this site closely parallel the demographics on Gene Expression).

Research seems to indicate that people are happiest when they're married, but that each child imposes a net decrease in happiness (parents in fact, enjoy a boost in happiness once their children leave the house). It's possible, of course, that adult children may be pleasurable to interact with, but it seems that in many cases, the parents want to interact with the children more than the children want to interact with the parent (although daughters generally seem more interactive with their parents).

So how do you think being child-free relates to rationality/happiness? Of course, Bryan Caplan (who is pro-natalist) cites research (from Judith Rich Harris) saying that parents really have less influence over their children than they think they have (so it's a good idea for parents to spend less effort in trying to "mold" their children, since their efforts will inevitably result in much frustration). And in fact, if parents did this, it's possible that they may beat the average.

(This doesn't convince me in my specific case, however, and I'm still committed to not having children).

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[-][anonymous]12y 12

I've wondered in the past if perhaps the best thing LW members could do if the singularity is more than 80 (4 generations) years away was simply to breed like Amish and adopt values of having many kids in the very late teens and early twenties early, focusing on higher education in the middling twenties and then after fifty spending most time on grandchildren whose parents followed the same patter and focus their late 20s and 30s on other goals.

Historical (Amish) population:

  • 1920 5,000
  • 1944 13,000
  • 1976 57,000
  • 1992 125,000
  • 2010 249,000

People underestimate just how much "dumb" replication can do to carry memes forward.

Edit: LW's help for a list of items is a bit confusing. If I remove item * in front of "historical Amish populations" from the above, the readable list of dates and population numbers collapses into a single poorly readable line. Can anyone explain this a bit further for me?

Either add 2 spaces to the end of the list header, or make sure there are two line breaks between it and the first item.

[-][anonymous]12y 0

Thank you.

LWers would not be the only ones to try this tactic, though. There's a whole movement based on producing more evangelical Christians.

Another tactic, better at changing ratios, would be to adopt existing children. This could propagate rationalists' memes, though not genes, and it's unpredictable how much those two things impact whether your children come out like you want (e.g. rationalist, or evangelical). And it assumes you want more rationalists compared to others, as opposed to just more rationalists, period.

[-][anonymous]11y 3

LWers would not be the only ones to try this tactic, though. There's a whole movement based on producing more evangelical Christians.

Well, yes. I did use Amish as the example of a group already using this tactic. But rationality is about winning, so clearly if rationalists put their minds to it they would be better at it. ;)

Another tactic, better at changing ratios, would be to adopt existing children.

Hey it worked for Shakers. Until government said no more mass adoptions for you.

What is P that government agencies might try to interfere with organizations that helped rationalist families adopts lots of kids? What is the P that some group might lobby and warn parents against giving away their children to those creepy/Godless people?

This could propagate rationalists' memes, though not genes, and it's unpredictable how much those two things impact whether your children come out like you want (e.g. rationalist, or evangelical).

Obviously enough evangelicals stay evangelicals for their group to keep growing. Amish reject many modern comforts, something evangelicals don't do, yet their losses aren't as great as people seem to think they would be.

But basically to the first approximation kids are like their parents in temperament and ability. And in the environment that LWers are likley to raise their kids its basically settled that nurture plays only a negligible role when explaining the differences between biological and adopted kids in the same family. Now lets consider which set of people have the temperaments and abilities better on average suited to our needs? Set of biological parents of children legally up for adoption or set of LWers?

And it assumes you want more rationalists compared to others, as opposed to just more rationalists, period.

More rationalists period sounds pretty awesome to me. Human brains are pretty much dirt cheap supercomputers that can actually do incredible things when hooked up together.

Another tactic, better at changing ratios

I'm responding a bit lightly and teasingly, so I should clear up that I'm not claiming this is most probably the best strategy, I haven't done much more than Fermi estimates, but so far its clear that its hard to deny it is a workable strategy.

And it keeps getting better and better looking the further away one puts his most likley singularity date, or even if one is sceptical of it ever occurring. But most LWers wouldn't think of it straight away as a potential strategy. I think the reason is that this strategy is currently employed by people LWers don't like, not only that it is a strategy that is low status in modern society. Perhaps we may be on average biased against it? No?

Again, my main point was this:

People underestimate just how much "dumb" replication can do to carry memes forward.

[-][anonymous]11y 0

I would guess focusing on other goals while raising multiple pre-teen/early-teen kids wouldn't be that easy.

[-][anonymous]11y 2

focusing on higher education in the middling twenties and then after fifty spending most time on grandchildren whose parents followed the same patter and focus their late 20s and 30s on other goals.

Proposed algorithm:

  1. Reproduce, early childcare
  2. Higher education (informal or formal)
  3. Other goals
  4. Raise multiple pre-teen/early-teen kids

Step one ends at about the early 20s, just as cognitive performance peaks. Still leaving time to make use of it for other achievements in the middling 20s. The obvious exception is really hard math, but fortunately most people in a viable population don't need to deal with really hard math.

Step three builds up resources and acheives other goals you estimate you won't be able to acheive after step four.

Step four raise your grandchildren or if you don't have those someone else's pre-teen/early-teen kids.

Current algorithm (for the demographic many LWers find themselves belonging to):

  1. Higher education (formal)
  2. Other goals
  3. Reproduce, maybe sort of
  4. Raise one or two teen kids maybe

I would argue that the quality of childcare isn't significantly diminished (if it is at all). There is indeed some opportunity cost here since is sub optimally employed cognitive horsepower. But the neat trick is that the new algorithm increases available cognitive horsepower every generation, while perhaps doubling or even tripling the number of highly trained rationalists. Also raising small children may leave you physically exhausted and be a time sink, but if you are provided resources by your parents or a community, that still leaves plenty of time to familiarize yourself with what you'll be doing in step two or even get the higher education done with. If parental funds are unavailable or insufficient there is work you can do to help cover the shortfall.

People can still do horizontal meme and mindware transmition with minimal losses in efficacy during "other goal" period or after they are done with phase four. Wasting peak reproductive time for that, is a really big waste of resources unless you are that rare exceptional person that started building the bedrock of the community.

[-][anonymous]11y 5

Also another neat function you can add, perhaps a bit tounge in cheek.

Immortality algorithm:

  1. Reproduce, early childcare
  2. Higher education (informal or formal)
  3. Other goals (if cryopatients can be revived go to 7)
  4. Raise multiple pre-teen/early-teen kids
  5. Make descendants swear to follow this algorithm.
  6. Become cryo patient
  7. Wake up (other) cryo patients and help them adjust to immortality and awesome stuff now available.

I should point out implementations of variations of this algorithm have proven to be wildly successful at keeping themselves running on groups of Homo Sapiens. But the problem is all the previous implementations had crappy cryo so no one actually got to step 7. :(

But now I've fixed this! Awesome. :D

[-][anonymous]11y 3

I get it now... The point is that while you're performing steps 2 and 3, your children will be taken care of by your parents (their grandparents), right?

[-][anonymous]11y 2

Yes.

[-][anonymous]12y 0

I think you need an extra carriage return after "population:"

Here it is without the extra line

  • more stuff

Here it is with an extra (blank) line

  • even more stuff

I realised early on I wanted children, and now I have one. (Watching this small intelligence develop is utterly riveting.) I'd like another, my girlfriend already has two others and really doesn't want a fourth!

This is not something that came from a rational decision. The desire came first, so the job of instrumental rationality as far as I was concerned was to make this work.

For those who have some desire for children but can't rationally make that work: may I strongly suggest sperm or egg donation. In the UK, they're terribly short of donor gametes (a shortage of over 200 donors a year), and having smart, rational people donate would probably be a net win for the gene pool at little personal cost (more faff in the case of eggs). If your sperm or eggs cope with freezing, you will reproduce.

If you're worried about your offspring being cast to the four winds, I wouldn't be too concerned - I was adopted, and it worked out I think because I was quite definitely wanted, not an accident. The children of your sperm or eggs will be very much wanted. It gives women the hitherto-unavailable option of passing on their genes with someone else doing the work of pregnancy.

And if the singularity takes more than twenty years, you'll have added a human of higher intelligence to the population.

In the US I've found most clinics are actually fairly picky about the traits they will accept in egg "donors"--who are usually reasonably well-compensated, which is, I suppose, why they can be so selective.

(I think it might be nice to pass on my genetic material. But no one paying through the nose--or any other orifice--for genetic material wants mine. Can't say I blame them.)

In the UK, as I said, they're desperate. IVF is a usably reliable technology, but the fact that it's the business of selling hope means that financial parasites have flocked to it, and that's led to heavy regulation ... heavy enough to put donors off. And payment is legally restricted to actual expenses, to a not very big upper limit. So the requirement is pretty much "don't have HIV or known genetic disorders."

So what I said above applies if you're in the UK. Get donating!

It strikes me as on-topic for a blog about rationality to describe my thinking processes concerning working out why I wanted children.

The urge is eminently biologically plausible - I come from a long line of successful replicators, after all. And just because this manifests itself as "I want sex" doesn't mean I don't also want the abstract result of sex. I also like the idea of bringing up a child.

But I had to justify the urge to myself, as the social circle I found myself in (punk-descended indie rock in Perth in the 1980s) tended to be very negative about having children. A few people had them, but many were powerfully negative about children, considering humans to be a curse upon the world, an ecological disaster, and the world to be too horrible to bring children into.

(This was the last decade of the Cold War, the feeling of which I find almost impossible to actually explain to almost anyone under thirty. We were young, but we seriously expected we could die with minutes of notice and were powerless to stop such a thing happening. It makes for good punk rock, but doesn't seem to me to have been a healthy environment.)

So I had to come up with rational justifications of my feelings. Of course, this sort of justification backwards from the predetermined outcome is highly improper. But it did come up with useful ideas for me to then attempt to play forward and examine closely: "my children will be an improvement in the world" (which I think is true) and "the world is not in fact awful, it's the best it's ever been" (which I also think was true and has continued to be true). This and "and anyway, I actually want to" was sufficient for me.

Note here that my thinking was not particularly clear (e.g. I privileged the hypothesis terribly), only sufficiently clear to satisfy me as to my own rightness in thinking differently to others around me. I am certainly not advocating the above as a model of how to think well, but as a case study in inchoate attempts at rational thinking about something personally important.

(And, by the way, many of those who expressed such opinions concerning children have since reproduced themselves.)

(This was the last decade of the Cold War, the feeling of which I find almost impossible to actually explain to almost anyone under thirty. We were young, but we seriously expected we could die with minutes of notice and were powerless to stop such a thing happening

This is worth noting. Contrary to the hindsight-ridden narrative of the Cold War that is common nowadays, according to which it had already wound down by the 1980s, there was in fact serious anxiety about a USA-USSR nuclear conflict almost right up to the dissolution of the latter country.

(The explanation for this narrative probably lies in the fact that it is often told by people who lived through the climax of the Cold War, i.e. the period of the Cuban Missile Crisis etc., or else by people too young to remember even the 1980s.)

Contrary to the hindsight-ridden narrative of the Cold War that is common nowadays, according to which it had already wound down by the 1980s

I'm ... boggling. Your statment is not implausible, but do you have links to such assertions?

Really, we thought we were likely to die at any time with no warning. When the Soviet Union collapsed and the Cold War was over, there was a zeitgeist of "... Um. OK. We're going to live. I have to plan now. Oh, God."

And as far as I can tell, the anxiety was there right up to the moment of collapse. Despite Gorbachev's excellent and calming media image in the final few years of it.

it is often told by people who lived through the climax of the Cold War, i.e. the period of the Cuban Missile Crisis

It is relevant, I think, that the "we" I speak of were young and powerless.

I know someone who had a child because the she felt enough better about the world after the Berlin Wall fell.

[-][anonymous]12y 2

My thinking was that since I obivously like anyone I decide to have children with and since the child's genes will be a mix of ours and the child is more likley to carry similar memes than a random one it serves my other values to adpot and promote "having children until indefinite lifespans or cryorevival are available" as a value.

However my adopting "having children" as a value hasn't yet resulted in me having any children.

Unfortunately I have a feeling that the loss of ability to consistently use contraception is much more robust than a positive desire to not use it when optimal, evolutionary speaking and that in the long run we can't really run away from this as long as agents keep replicating.

(This was the last decade of the Cold War, the feeling of which I find almost impossible to actually explain to almost anyone under thirty. We were young, but we seriously expected we could die with minutes of notice and were powerless to stop such a thing happening. It makes for good punk rock, but doesn't seem to me to have been a healthy environment.)

Two thousand zero zero, party's over, oops out of time...

I've seen these sort of claims before and I've never seen a plausible rejoinder to the issue of correlation v. causation. In particular, unhappy people may actually be more likely to have children for some reason. The most obvious way to test this is to repeatedly ask how happy people are and see if it drops when some of them have kids.

In my experience, my probability of having children and my desire to have them are highly correlated with my happiness going up. Primarily I believe this is common cause, as the factors that make me happier also make it far more attractive and practical to have children. Other comments have noted events in the world that made them happy and also made them more inclined to have children.

However, it is also clear that those who come from wealthy or generally happier classes and backgrounds are far less likely to have children; the countries and areas with high birth rates are usually relatively unhappy and the most happy ones are below replacement.

This implies that it probably depends how you find the people for your study. If you're looking for similar backgrounds and then seeing who has children, I'd expect the ones with children to have previously been happier. If you're sampling randomly from the world I'd be confident in the opposite but I've never heard of doing a study that way.

Cultural and developmental factors (some people being more likely both to be rational and not want kids for external reasons) are going to swamp pure "rationality" on this subject. Which means we don't have a control group, or even a particularly clear idea of what a control group would look like.

So I agree with David Gerard's more introspective approach - the most rational thing to do seems to be to figure out exactly what we think we know about having children vis a vis our ideas of what would be a good idea.

So, doing just that: my main rational aversion to having kids is that it takes a lot of time, and I value my time pretty highly. My main emotional aversion (emotional reasons tending to be deceptively powerful) is that raising a kid seems like it would require things that I am utterly unprepared for - by which I mostly mean social skills, I'm not scared of changing a diaper. I could learn them, almost certainly, but that doesn't dissolve the feeling of unpreparedness.

Upon introspection, maybe I just don't think kids are as interesting as other people do because I connect with people on a mainly intellectual level, which would be a general argument. But that depends on the child - I probably would find my past self likeable and my past activities interesting-ish above age 8. But still, maybe other people find doing things like watching kids' soccer games enjoyable where I would bring a book.

As for the good parts, the best seems to be that you get to make a new person. Possibly a cool person, who makes you feel a sense of pride and love every time you see them. I'd probably learn all those skills I mentioned, and plenty more that I wasn't even thinking of. I'd understand people better. I'd have someone to take care of me in my old age, which could be nice even if my old age doesn't involve a dying body.

I suppose I'm still undecided.

I was a lot like this. I didn't end up having my child until I was 40, after something somewhat resembling an overextended adolescence. I think it was feeling I'd found just the right partner.

In any case, I knew I wanted children but didn't feel ready, then I did feel this could work when I was with someone I felt I could raise children with for the next couple of decades. And so far it's going pretty well.

(And then the teenagers landed on our doorstep, so I got to experience adolescent angst from the outside about a decade earlier than I'd expected. FUN TIMES!)

I do regret not having as much freedom to party and get drunk and chase loose persons. On the other hand, my offspring is (as any father will tell you) the most beautiful and charming child in the world, when I say "she's so smart!" there's a shudder in my voice and we have realised the important goal here is to steer her away from becoming the next Dark Lord. She likes hissing like a snake already.

In general, the most difficult task in my life has been to work out what I actually really want: what will satisfy me. Note I say "satisfy me" rather than "make me happy" - I'm much clearer on the former as a guiding principle than the latter. For many people, the hardest part of getting things done is to work out what it is they really want to get done - what their true goals are.

I once knew a couple who referred to their one year old daughter as the "evil overlord." I'm not completely unworried what happened to her.

I have a child, and plan on having more - both because I like kids, and because it's the right thing to do.

Evidence that children make parents less happy won't make me change my mind any more than learning that I would be happy by wireheading, taking drugs or becoming a Christian.

Do you have any actual evidence for it being the "right" thing to do?

Not really - or rather, I'm not quite sure what would consitute "evidence" for moral questions.

To take a simpler example, most people would agree that it's the right thing to jump into a river to save a drowning toddler, even if there's a slight risk to your own life (the current is strong) and it's certain to damage your clothes and smartphone. Yet I don't see what would consitute "evidence" that it's the right thing to do.

(edit) But if you're asking about reasons for believing it's the right thing, I'd say that the future world would likely be a better place if wealthy, educated and responsible people have more kids.

[-][anonymous]12y 3

Many people seem to be arguing abut the effects on happiness. I'm not too concerned about that to be honest. The negative effect on happiness doesn't seem radical and child outcomes aren't that much effected by parental upbringing beyond a minimum once one disentangles the data from genetics so I'm not to worried about responsibility, especially since I think that by the early 20s he is as much a independent agent as anyone today and I don't feel (yes horrible word) like someone else is responsible for my actions. Financial independence is another issue, however again genetics will play a large role in reducing my child's risk for some kinds of poor decisions so really my decisions should mostly be based on my genes.

Not everything that I do pursuing my values will make me happy, especially if some of my values can't really be lived up to by humans.

If one day I notice that I want to have children, I will have to weigh that against well-supported research that shows having children decreases happiness. Even if I feel that I very strongly want children, I would consider that to be very weak evidence that I would go on feeling so for 20-30 years (time needed to raise child to independence). The evidence of the research would be more weighty than my own feelings.

(Anecdotally, what I actually feel is that having children is utterly horrible.)

One could argue that it would result in a net happiness, as children tend to help their parents when they get older. My parents helped grandfather's medical needs, and probably extended his life by about 5 years.

There is no such concept as "rationality/happiness".

I read that as "So how do you think being child-free relates to rationality? Happiness?", which would be understood as "So how do you think being child-free relates to rationality? How do you think it relates to happiness?"

Okay sure, but isn't utilitarianism usually conceived of as "what contributes to the maximum average happiness?" And do most people here conceive of a basis of rationality with an end other than happiness? (I mean, there are ways if you define the end in another way, such as satisfaction, but do many people here do that?)

(I mean, there are ways if you define the end in another way, such as satisfaction, but do many people here do that?)

I do, and I suspect I'm not the only one.

Utilitarianism originally showed up as what you think, but it has changed rather drastically. See "preference utilitarianism," for the main change, iirc.

And do most people here conceive of a basis of rationality with an end other than happiness?

Forgive me if this is totally obvious and not helpful, but have you seen this post?

Oh okay thanks - I just wasn't here during this site's early days.

And this is why theists always outnumber atheists.

Yes, that's true. The thing is this: it is rational for each of us to be childless, even though childlessness is not collectively rational for us all. It's sort of like a prisoner's dilemma with many people in it.

it is rational for each of us to be childless

I find this statement highly questionable standalone. Rational given what aims?

It's sort of like a prisoner's dilemma with many people in it.

This, however, explains people who get incredibly upset at the notion of others not wanting children and brand them "selfish".

[-][anonymous]12y 0

Very important. Any memeplex that has aims that happen to produce kids will have a edge. It just so happens few if any secular memplexes have made this possible.

But this is odd especially since values are arbitrary, is there really no value one can pursue that is best served (among other things) in having children (and perhaps attempt to imprint the same values on them)?

This, however, explains people who get incredibly upset at the notion of others not wanting children and brand them "selfish".

Its the same kind of upset a different kind of people have when they don't see someone ,who has already heard all the arguments for it, recycling.

Very important. Any memeplex that has aims that happen to produce kids will have a edge. It just so happens few if any secular memplexes have made this possible.

Another way a memeplex can succeed is by being very good at converting others. Note that such a memeplex if left unchecked could cause humans, or at least whatever culture it spreads in to evolve to extinction. As such leaders of other memeplexes may take extreme measures to suppress it.

[-][anonymous]12y 0

Agreed. However very virulent memeplexes are unlikley to be attacked, they will quickly gain sympathy in nearly any organization.

Also known as a "Tragedy of the Commons".

You can also think of it as evolution selecting against atheism.

[-][anonymous]12y 0

You can think of it as evolution selecting against people who don't want children.

Eliezer discusses a situation like this here.

France, the Nordic countries, the Czech Republic, the Baltic countries, am I forgetting someone? oh, yes, and China beg to differ.

France, the Nordic countries, the Czech Republic, the Baltic countries, am I forgetting someone? oh, yes, and China beg to differ.

I would simply like to mention that all those countries have sub-replacement fertility.

[-][anonymous]12y 0

From which I think it follows that atheists in those countries must either raise their birth rates or be very efficient at getting new immigrants from elsewhere to abandon their religions for these to be sustainable.

[-][anonymous]12y 1

Its not theism in itself. And I would argue its not rationality in itsef for a sufficient value of well... values.

Compare the fate of the very pious and irrational Amish (a table of who's demographic success I present in another comment) to the very pious and irrational shakers.

Membership in the Shakers dwindled in the late 19th century for several reasons: people were attracted to cities and away from the farms; Shaker products could not compete with mass-produced products that became available at a much lower cost; and Shakers could not have children, so adoption was a major source of new members. This continued until the states gained control of adoption homes. Some Shaker settlements, such as Pleasant Hill community in Kentucky, and Canterbury, New Hampshire, the latter of which died with its last member, Ethel Hudson, in September 1992,[6] have become museums.

Although there were six thousand believers at the peak of the Shaker movement, there were only twelve Shaker communities left by 1920. In the United States there is one remaining active Shaker community, at Sabbathday Lake, Maine, which as of September 2010 has only three members left, Sister June Carpenter, Brother Arnold Hadd, and Sister Frances Carr [7] [3][8]. The Sabbathday Lake community still accepts new recruits, as it has since its founding. Shakers are no longer allowed to adopt orphan children after new laws were passed in 1960 denying control of adoption to religious groups, but adults who wish to embrace Shaker life were welcome. This community, founded in 1782, was one of the smaller and more isolated Shaker communities during the sect's heyday. They farm and practice a variety of handicrafts; a Shaker Museum, and Sunday services[9] are open to visitors. Mother Ann Day is celebrated on the first Sunday of August. The people sing and dance and a Mother Ann cake is presented.

As a note of interest let me just point out that both groups where for a extended period of time of a size comparable to the number of regular LW readers.

Nevertheless, fertility is inversely correlated with most measures of intelligence and rationality.

You can look at the wikipedia article Fertility and intelligence and its references for starters.

[-][anonymous]11y 0

The labour involved in raising kids has a higher opportunity cost for more competent people. Also due to regression to the mean, very intelligent people are unlikely to have children smarter than them so this may reduce rewards.

Intelligent, rational people not having kids is basically a tragedy of the commons. Everyone is better of (including the unintelligent and irrational) if this group has more children, but for each individual it is a pretty burdensome undertaking (even when taking into account selfish reasons to have kids) And our whole modern status system is unfortunately built in such a way that it exacerbates the problem rather than alleviating it.

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I would guess that fertility would correlate most strongly with precisely average intelligence and precisely average levels of rationality. There's a reason the normal distribution tapers at both ends.

This may not be true depending how much we've changed our selection pressures with this "civilisation" palaver. That said, I too would like a citation please.

[-][anonymous]12y 3

From what I know people of below average intelligence have higher fertility than people of average intelligence. I think modern civilization has changed the selective pressures massively from the ones that produced the current averages.

One of the sources off the top of my head

The pattern though it holds overall obviously isn't uniform for all groups, Black males for example do seem to in the US to be enjoying slight positive selection for a higher mean IQ (I need to crunch the numbers to see if this is so) or at least have peak fertility at about the US mean IQ, which is good. What concerns me however is the gender difference in these pressures (graph from the paper I link to). I fear that we will be selecting for gender dimorphism in abilities until we hit better reproductive technology. Prolonged education in a meritocracy is bound to eat up more female than male fertility due to the lost peak years of reproduction. Also we have the problem of men caring less about the socio economic status of the partners they choose to reproduce with than women. Extra status buys men more reproductive options later in life than it does for women in the same age bracket. This sucks quite a bit.

The artificial uterus can't come quick enough. Thought I think life extension and rejuvenation tech could also help if we could make pregnancies in the 50s and 60s healthy and convenient.

Mutation-selection equilibrium. We get dozens of new mutations each generation, and it takes generations of selective pressure to expunge new deleterious ones.

I wonder how much fertility varies with beauty?

[-][anonymous]12y -2

If this is true for all memplexes, values and natural personality variations and the singularity doesn't come in the next 30 years humans are pretty screwed.

The odd thing is that the Shakers seem to have been unusually rational about designing what they made.

I'd like to see more detail about the claim that having children is likely to make people less happy-- in particular, whether it makes the vast majority of people less happy, or whether it makes some people unhappy, and leaves others at the same happiness level or perhaps even makes them happier. If it's the latter (and I suspect it is) then rationalists would have a better chance of evaluating whether having children is likely to improve their lives, and more generally, there would be ways to find out how to make it easier for parents to enjoy having children.

There's no question having a child is highly variant in its outcome, both in terms of happiness and otherwise. It makes some people radically happier, and some people radically unhappier. If the effect was reliable then given its magnitude we wouldn't have any difficulty recognizing it casually.