> What I mean is that I can clearly see the logic here, but I'd love to see a discussion for instance on the continual existence of evolutionary destructive tra

> What I mean is that I can clearly see the logic here, but I'd love to see a discussion for instance on the continual existence of evolutionary destructive traits such as homosexuality, which by all accounts has not only been around for a great deal of human existence, but also other species. It allows excess parents without having excess children. Assume your objective function is to pass along genetic material that is similar to your own. Depending on your resource constraints of your environment and how close your population is to its carrying capacity, it may be game-theoretically optimal to help raise your sibling's child, rather than produce your own. If your child lowers the resources available per child for all your immediate relatives, you would be better off trying to increase the survival rate of an existing closely-related child instead. Thus, a gene that occasionally produces non-breeders (especially if the chance is modulated by relevant environmental factors) will, when properly tuned, result in a larger number of successful children. The bigger lesson is, look at the genetic distribution of the population, not necessarily the genetics of the individuals. Humans live in groups and interact with each other, so things that don't make sense for the individual can still work. As an analogy: doctors increase everyone's survival rate, so you want lots of doctors right? Well, no, then no one would make food and we would starve. But that doesn't mean doctors are bad, either. It means you want some percentage of the population to be doctors, and that percentage is neither 0% nor 100%.