“Potential autofertility in true hermaphrodites”[1] by Istanbul urologist Zeki Bayraktar is among the most bizarre articles I have encountered in a peer-reviewed medical journal. Though the abstract and first few pages contain a secular discussion of intersex conditions, the paper abruptly pivots to an explanation for the birth of Jesus Christ. This theological tangent concludes, “According to Qur’an, it can be said that Mother Mary was a true hermaphrodite, who did not have ambiguous genitalia, with a normal female phenotype, became pregnant through self-fertilization, and gave birth to a healthy baby boy (Jesus).”
As an atheist, “Mary was a true hermaphrodite” sounds a little heretical, as does the cited opposing theory that Mary became pregnant through parthenogenesis and Jesus was chromosomally female.[2] But what do I know.
Theology aside, is Bayraktar right? Is autofertility possible in humans?
Bayraktar himself makes a poor case for autofertility in humans, stating unconvincingly that “at least we cannot say that it is impossible for sure.” As far as Bayraktar and I am aware, there has never been a documented case of an individual conceiving a child through autofertilization. Nor has there been a documented case of an individual being both the genetic mother and father of separate children. But this isn’t a huge knock on possibility when we’re discussing a situation already understood to be vanishingly rare,[3] and the technology required to reliably document either case has only existed since the 1990s, after the adoption of modern medical practices that, as I’ll discuss later, artificially suppress these phenomena.
Since I’m more interested in biotechnology than I am in biotheology, I don’t need to restrict my scope to fully unassisted autofertilization of the kind that could occur 2000 years ago. Allowing still-speculative in vitro gametogenesis into consideration would defeat the point, but IVF, ICSI, IVM, and surrogacy are established reproductive technologies that grant anyone who produces both fertile sperm and eggs (call this “bisexual fertility”) the capacity for autofertilization, even if they cannot impregnate themselves or carry a pregnancy.
Great. Now we just need evidence that some humans can produce both fertile sperm and eggs.
Some humans produce both fertile sperm and eggs
The patient from Shannon & Nicolaides (1973).
There are multiple case studies showing histological evidence of individuals producing both sperm and eggs:
Shannon & Nicolaides (1973)[4] described a 31 year old man[5] with a left scrotal testicle and right internal ovary. The ovary, alongside the fallopian tube and underdeveloped uterus it was attached to, was surgically removed. They found a developing ovum, primordial ova, as well as corpora albicantes and a corpus luteum, evidence of prior ovulation. Seminal analysis found 20 * 10^6 sperm/ml, with 60% motile and morphology “within normal limits.” The man had a healthy 2 year old daughter and 7 year old son, but no paternity verification was done, and prior fertility issues were reported.
Parvin (1982)[6] described a 32 year old man, also with a left testicle and right ovary. The ovary was removed and found to have “normal ovarian stroma with several Graafian follicles and primordial follicles containing immature ova… ovulation was assumed to have occurred at some time given the presence of corpora albicantes.” After surgery, “seminal analysis revealed 15 * 10^6 sperm/ml with 60 percent motility and 8 per cent abnormal forms.” The man had a healthy 20 month old daughter, but (say it with me) no paternity verification was done, and prior fertility issues were reported.
van Bever et al. (2018)[7] described a 19 year old man, with a left scrotal testicle and right scrotal ovotestis. To what I can only assume to be great frustration on the researcher’s part, given how much effort they put into analyzing this guy’s biology, the patient refused to provide a sperm sample for analysis. Still, immunohistological analysis found evidence for spermatogenesis in the testicular tissue of the ovotestis, with spermatogonia present in seminiferous tubules. Ovarian tissue had follicles that had been causing recurring cysts likely due to a ovulatory cycle, complete with characteristic LH surges.
Sy et al. (2024)[8] described described a 31 year old man, with a right scrotal testicle and left internal ovary. The ovary, alongside tube and undeveloped uterus, was removed, and found to have “oocytes at different stages of maturation” without mention of evidence for ovulation. 1.8 * 10^6 sperm/ml, 15% mobility, with only 2% of typical morphology.
All of these patients appeared to have a mixed[9] 46,XX/XY karotype, though Shannon & Nicolaides (1973) lacked the evidence to verify this due to technological limitations. This is not the only karotype that could possibly enable bisexual fertility, but it is the most likely.[10]
It’s also no coincidence that all the patients were adult men, whose intersex condition was discovered later in life. 46,XX/XY individuals can have a wide spectrum of biological features, and both male and female fertility has been separately documented, but fertile sperm is much rarer than fertile eggs. Spermatogenesis is much more fragile than oogenesis, and easily disrupted by high temperatures (associated with internal gonads) or excess estrogen (associated with feminine phenotype). Having the right physiological features to enable spermatogenesis goes hand-in-hand with having a predominantly male phenotype.
We can’t prove that the eggs produced by any of the four individuals described above definitely would have been fertile: the only way to know for sure is to make a baby. Since paternity verification wasn’t done by Shannon & Nicolaides (1973) or Parvin (1982), we can’t even be sure anyone’s sperm was fertile. But we do have proof that people with the same karotype and similar features can be fertile as male or female, and we have evidence of some normal-appearing gametes and associated structures in the four individuals. While we can’t be certain any specific individual is bisexually fertile, we can be certain that some humans are.
Modern medical practices artificially suppress bisexual fertility
When I brought up the case studies above to friends that are normally knowledgeable on weird biological anomalies, they were surprised. “I thought that hadn’t been documented in humans” was a common response I got both from friends and online, and indeed, “simultaneous sperm and egg production has never been documented in humans” is claim I often encountered floating around on the internet, and from popular LLMs.
I suppose "verified," "fully fertile," and "confirmed documented" are all subjective judgments, but I still think these Claude Opus 4.8 High and ChatGPT 5.5 Instant responses are inaccurate given the actual available evidence. It suggests "this is impossible" instead of "this is highly probable, but 100% verification is impractical, so we only have lesser evidence."
It’s not entirely unreasonable to draw your line for “documented” at “make a baby or bust,” but it’s surprising how many people believe simultaneous sperm and egg production is somehow impossible. Rather, we have strong evidence it happens, and researchers in the field have found that fact uncontroversial since the 80s, which is exactly why nobody but biotheologists are motivated to “prove it.”
Studies on the fertility of intersex people focus only on the biological functions corresponding to the individual’s assigned gender, and rarely investigate fertility potential for both gamete types. For adult patients, this is usually consistent with the patient’s interest: if you’re an average man that shows up to a fertility clinic because you’re trying to have kids with your wife, and the doctor finds your issues are caused by you having an ovary, you wouldn’t care whether you have fertile eggs. But this tendency is troubling with child patients, where clinicians fail to consider that an infant raised as a boy might grow up to appreciate having an ovary, or even recommend gender reassignment on the basis of which gametes they think are more likely to be fertile.
The patient, [a six-month-old infant] initially assigned male, is currently under follow-up by a multidisciplinary team. The parents are open to reconsidering the child’s sex based on gonadal function assessment results and future fertility prospects. Surgical interventions and hormonal treatments will be evaluated in light of these factors. - Hssaini et al. (2024)[11]
While bisexual fertility is rare by any measure, it is made more rare by modern medical practices, and the social structures around them.
As a matter of ethics, I am opposed to unnecessary medical interventions on patients too young to have an opinion on the matter, a practice which resulted in the famous M.C. v. Aaronson lawsuit. Many intersex individuals benefit from medical interventions, but most can be delayed until the start of puberty or later.
As a matter of scientific curiosity, I’m annoyed that premature removal of gonadal tissue without preservation efforts takes away another chance for someone to become the genetic mother and father of (hopefully different) children. Most people lack the resources and inclination for that even if they had the biology for it, but there are some weirdos who would delight to set the record. At this rate, we’re going to have to wait until in vitro gametogenesis before we get bisexual reproduction.
Autofertilization has probably never happened in humans
While autofertility in humans is feasible by some rare individuals using available technology, autofertilization has probably never happened. Unassisted autofertilization is much harder than merely producing sperm and eggs: among other things, it also requires a fully functioning uterus. Not impossible, but improbable enough that it might have never happened. And if technologically assisted autofertilization has ever happened, it would’ve been documented.
This is for the best. Autofertilization is genetically equivalent to sibling incest if the parent is a tetragametic chimera, and worse than sibling incest for some other kinds of chimerism or mosaicism.
Which makes me think back to Dr. Bayraktar. As an atheist, “Jesus was biologically an incest baby” sounds a little heretical. But what do I know?
This theory was proposed by biologist Edward L. Kessel, who describes an “androgynous Christ” that “assumed the phenotype of a man while retaining the chromosomal badge of a woman.” While I can respect efforts to reconcile science and religion, I confess I don’t understand the motivation here. Aren’t miracles supposed to defy explanation? If there are any Abrahamic biotheologists reading this, please weigh in.
This patient had a predominantly male phenotype and was socially and legally male. There is no non-confusing way to talk about this, sorry. Be glad that unlike the literature, I don’t drop terms like “male hermaphrodite” and expect you to understand what that means.
van Bever et al. (2018) identified their patient as a tetragametic chimera (originating from two sperm/egg pairs), and Sy et al. (2024) identified theirs as a chimera without further specificity. Many forms of chimerism and mosaicism could cause 46,XX/XY.
Something like 46,XX/XXY could be possible, for example. I am not aware of any documented cases of an XX individual producing sperm or an XY individual producing eggs, and while I would not call it impossible, it’s unusual enough that a case study of such phenomena would tell us new things about gametogenesis.
One 46,XY/X0 mosaicism case comes pretty close to the latter. The paper describes a woman with a predominantly XY karotype that “underwent spontaneous puberty, reached menarche, menstruated regularly, experienced two unassisted pregnancies, and gave birth to a 46,XY daughter with complete gonadal dysgenesis,” and contains what might be a brand new sentence, “Evaluation of the Y chromosome in the daughter and both parents revealed that the daughter inherited her Y chromosome from her father.”
“Potential autofertility in true hermaphrodites”[1] by Istanbul urologist Zeki Bayraktar is among the most bizarre articles I have encountered in a peer-reviewed medical journal. Though the abstract and first few pages contain a secular discussion of intersex conditions, the paper abruptly pivots to an explanation for the birth of Jesus Christ. This theological tangent concludes, “According to Qur’an, it can be said that Mother Mary was a true hermaphrodite, who did not have ambiguous genitalia, with a normal female phenotype, became pregnant through self-fertilization, and gave birth to a healthy baby boy (Jesus).”
As an atheist, “Mary was a true hermaphrodite” sounds a little heretical, as does the cited opposing theory that Mary became pregnant through parthenogenesis and Jesus was chromosomally female.[2] But what do I know.
Theology aside, is Bayraktar right? Is autofertility possible in humans?
True to stereotype, rabbits have been documented exhibiting autofertility. Image of a rabbit that is probably not a hermaphrodite by JM Ligero Loarte.
Bayraktar himself makes a poor case for autofertility in humans, stating unconvincingly that “at least we cannot say that it is impossible for sure.” As far as Bayraktar and I am aware, there has never been a documented case of an individual conceiving a child through autofertilization. Nor has there been a documented case of an individual being both the genetic mother and father of separate children. But this isn’t a huge knock on possibility when we’re discussing a situation already understood to be vanishingly rare,[3] and the technology required to reliably document either case has only existed since the 1990s, after the adoption of modern medical practices that, as I’ll discuss later, artificially suppress these phenomena.
Since I’m more interested in biotechnology than I am in biotheology, I don’t need to restrict my scope to fully unassisted autofertilization of the kind that could occur 2000 years ago. Allowing still-speculative in vitro gametogenesis into consideration would defeat the point, but IVF, ICSI, IVM, and surrogacy are established reproductive technologies that grant anyone who produces both fertile sperm and eggs (call this “bisexual fertility”) the capacity for autofertilization, even if they cannot impregnate themselves or carry a pregnancy.
Great. Now we just need evidence that some humans can produce both fertile sperm and eggs.
Some humans produce both fertile sperm and eggs
The patient from Shannon & Nicolaides (1973).
There are multiple case studies showing histological evidence of individuals producing both sperm and eggs:
All of these patients appeared to have a mixed[9] 46,XX/XY karotype, though Shannon & Nicolaides (1973) lacked the evidence to verify this due to technological limitations. This is not the only karotype that could possibly enable bisexual fertility, but it is the most likely.[10]
It’s also no coincidence that all the patients were adult men, whose intersex condition was discovered later in life. 46,XX/XY individuals can have a wide spectrum of biological features, and both male and female fertility has been separately documented, but fertile sperm is much rarer than fertile eggs. Spermatogenesis is much more fragile than oogenesis, and easily disrupted by high temperatures (associated with internal gonads) or excess estrogen (associated with feminine phenotype). Having the right physiological features to enable spermatogenesis goes hand-in-hand with having a predominantly male phenotype.
We can’t prove that the eggs produced by any of the four individuals described above definitely would have been fertile: the only way to know for sure is to make a baby. Since paternity verification wasn’t done by Shannon & Nicolaides (1973) or Parvin (1982), we can’t even be sure anyone’s sperm was fertile. But we do have proof that people with the same karotype and similar features can be fertile as male or female, and we have evidence of some normal-appearing gametes and associated structures in the four individuals. While we can’t be certain any specific individual is bisexually fertile, we can be certain that some humans are.
Modern medical practices artificially suppress bisexual fertility
When I brought up the case studies above to friends that are normally knowledgeable on weird biological anomalies, they were surprised. “I thought that hadn’t been documented in humans” was a common response I got both from friends and online, and indeed, “simultaneous sperm and egg production has never been documented in humans” is claim I often encountered floating around on the internet, and from popular LLMs.
I suppose "verified," "fully fertile," and "confirmed documented" are all subjective judgments, but I still think these Claude Opus 4.8 High and ChatGPT 5.5 Instant responses are inaccurate given the actual available evidence. It suggests "this is impossible" instead of "this is highly probable, but 100% verification is impractical, so we only have lesser evidence."
It’s not entirely unreasonable to draw your line for “documented” at “make a baby or bust,” but it’s surprising how many people believe simultaneous sperm and egg production is somehow impossible. Rather, we have strong evidence it happens, and researchers in the field have found that fact uncontroversial since the 80s, which is exactly why nobody but biotheologists are motivated to “prove it.”
Studies on the fertility of intersex people focus only on the biological functions corresponding to the individual’s assigned gender, and rarely investigate fertility potential for both gamete types. For adult patients, this is usually consistent with the patient’s interest: if you’re an average man that shows up to a fertility clinic because you’re trying to have kids with your wife, and the doctor finds your issues are caused by you having an ovary, you wouldn’t care whether you have fertile eggs. But this tendency is troubling with child patients, where clinicians fail to consider that an infant raised as a boy might grow up to appreciate having an ovary, or even recommend gender reassignment on the basis of which gametes they think are more likely to be fertile.
While bisexual fertility is rare by any measure, it is made more rare by modern medical practices, and the social structures around them.
As a matter of ethics, I am opposed to unnecessary medical interventions on patients too young to have an opinion on the matter, a practice which resulted in the famous M.C. v. Aaronson lawsuit. Many intersex individuals benefit from medical interventions, but most can be delayed until the start of puberty or later.
As a matter of scientific curiosity, I’m annoyed that premature removal of gonadal tissue without preservation efforts takes away another chance for someone to become the genetic mother and father of (hopefully different) children. Most people lack the resources and inclination for that even if they had the biology for it, but there are some weirdos who would delight to set the record. At this rate, we’re going to have to wait until in vitro gametogenesis before we get bisexual reproduction.
Autofertilization has probably never happened in humans
While autofertility in humans is feasible by some rare individuals using available technology, autofertilization has probably never happened. Unassisted autofertilization is much harder than merely producing sperm and eggs: among other things, it also requires a fully functioning uterus. Not impossible, but improbable enough that it might have never happened. And if technologically assisted autofertilization has ever happened, it would’ve been documented.
This is for the best. Autofertilization is genetically equivalent to sibling incest if the parent is a tetragametic chimera, and worse than sibling incest for some other kinds of chimerism or mosaicism.
Which makes me think back to Dr. Bayraktar. As an atheist, “Jesus was biologically an incest baby” sounds a little heretical. But what do I know?
Bayarktar, Zeki. (2017). Potential autofertility in true hermaphrodites. The Journal of Maternal-Fetal & Neonatal Medicine. 31. 1-10. 10.1080/14767058.2017.1291619.
This theory was proposed by biologist Edward L. Kessel, who describes an “androgynous Christ” that “assumed the phenotype of a man while retaining the chromosomal badge of a woman.” While I can respect efforts to reconcile science and religion, I confess I don’t understand the motivation here. Aren’t miracles supposed to defy explanation? If there are any Abrahamic biotheologists reading this, please weigh in.
Even “messiah” rare.
Shannon, R., & Nicolaides, N. J. (1973). True Hermaphroditism with Oogenesis and Spermatogenesis. Australian and New Zealand Journal of Obstetrics and Gynaecology, 13(3), 184–187. Portico. https://doi.org/10.1111/j.1479-828x.1973.tb02304.x
This patient had a predominantly male phenotype and was socially and legally male. There is no non-confusing way to talk about this, sorry. Be glad that unlike the literature, I don’t drop terms like “male hermaphrodite” and expect you to understand what that means.
Parvin, S. D. (1982). Ovulation in a cytogenetically proved phenotypically male fertile hermaphrodite. Journal of British Surgery, 69(5), 279–280. https://doi.org/10.1002/bjs.1800690517
Yolande van Bever, Katja P. Wolffenbuttel, Hennie T. Brüggenwirth, Eric Blom, Annelies de Klein, Bert H.J. Eussen, Florijn van der Windt, Sabine E. Hannema, Arianne B. Dessens, Lambert C.J. Dorssers, Katharina Biermann, Remko Hersmus, Yolanda B. de Rijke, Leendert H.J. Looijenga; Multiparameter Investigation of a 46,XX/46,XY Tetragametic Chimeric Phenotypical Male Patient with Bilateral Scrotal Ovotestes and Ovulatory Activity. Sex Dev 22 February 2018; 12 (1-3): 145–154. https://doi.org/10.1159/000479946
Sy, M., Dial, C., Ibondou, R., Diallo, A., Ba, A. and Faye, O. (2024) 46,XX/46,XY Chimera with Ovotesticular Disorder of Sex Development (OT-DSD): A Rare Entity. Open Journal of Genetics, 14, 77-86. doi: 10.4236/ojgen.2024.144006.
van Bever et al. (2018) identified their patient as a tetragametic chimera (originating from two sperm/egg pairs), and Sy et al. (2024) identified theirs as a chimera without further specificity. Many forms of chimerism and mosaicism could cause 46,XX/XY.
Something like 46,XX/XXY could be possible, for example. I am not aware of any documented cases of an XX individual producing sperm or an XY individual producing eggs, and while I would not call it impossible, it’s unusual enough that a case study of such phenomena would tell us new things about gametogenesis.
One 46,XY/X0 mosaicism case comes pretty close to the latter. The paper describes a woman with a predominantly XY karotype that “underwent spontaneous puberty, reached menarche, menstruated regularly, experienced two unassisted pregnancies, and gave birth to a 46,XY daughter with complete gonadal dysgenesis,” and contains what might be a brand new sentence, “Evaluation of the Y chromosome in the daughter and both parents revealed that the daughter inherited her Y chromosome from her father.”
Hssaini, M., Bourkadi, G., Ahakoud, M., Bouguenouch, L., Abourazzak, S., Bekkari, H., & Ameli, A. (2024). A Case Report of a Rare 46,XX/47,XXY Mosaicism With Ovotesticular Disorder of Sex Development and a Literature Review. Cureus, 16(7), e65856. https://doi.org/10.7759/cureus.65856