"If enough people adopt children and then encourage those children to adopt when they're older, it could easily outweigh genetic effects"
And that will only provide a more fertile ground for proliferation of a specific kind of genes, don't you think? (Of course, for that you must have to believe at least a little bit that genetic behavior is not entirely replaceable by parental education.) Currently, if having a harsh life as an abandoned child is something of a lesson to prevent a similar experience in one's offsprings (which are cared for), then through each adoption we're just preventing/affecting a natural homeostasis.
And that will only provide a more fertile ground for proliferation of a specific kind of genes, don't you think? (Of course, for that you must have to believe at least a little bit that genetic behavior is not entirely replaceable by parental education.) Currently, if having a harsh life as an abandoned child is something of a lesson to prevent a similar experience in one's offsprings (which are cared for), then through each adoption we're just preventing/affecting a natural homeostasis.