Gee, well it's not like you're contributing to that problem.

You might as well bow out before busting out the ad homs.

so it's just got to be genes, right

Eugine_Nier never said it was "just" the genes, on the contrary. If you were making the claim that genes are not involved, the onus is on you to show so. Asking for evidence isn't an argument from ignorance. It would be astounding if there were genetic variations leading to endless variations in everything except cognition. The default assumption (even with no cognition-specific data) is "everything is affected by genetics". The degree may well be lower than individual variations, it would still shift the mean and lead to an overall difference between groups.