This is tangential to your point, but what would you say to a utilitarian who says:

"Evolution (memetic evolution, that is) has instilled in me the idea of that I should linearly value the welfare of others regardless of kinship, regardless of what instincts I got from my genes."

Since such a belief is pretty potentially disasterous for the genes - so: how come it got through the memetic immune system? Perhaps this is a case of meme evolution outstripping gene evolution, resulting in virulent memes that can memetically hijack people's brains. However, many seem to have working immune systems - and can resist this meme. Do the utilitarians have weakened memetic immunity? What can have led to that? Were they not taught about the risks of memetic hijacking in school - or by their families?