I've once heard that some forms of terrorism might be genetically beneficial. The logic goes, if one person can become a local patriotic or religious hero, and get their family a bunch of status or money, and therefore increase the likelihood their siblings reproduce, they're actually maximizing genetic inclusive fitness through a seemingly insane strategy. Similar claims get made about gay men - that they weren't completely bred out because in the past they were an adaption to decrease competition and increase the chance their siblings and cousins get married and have kids within small, rural areas.
Could the same be true about people who commit suicide? If so, wouldn't people who commit suicide tend to have more siblings than those who don't? I know people aren't actually thinking this when they attempt suicide, and that evolution hasn't necessarily encoded this strategy into people even if it's part of the explanation, but it would be interesting to check.