Nature vs. Nurture is very much not a settled argument. Although if anything, recent understanding in epigenetics movers the needle a bit more in the "nurture" direction.

The interaction surface between genetics and physiology itself is very complex and not well understood. The interaction surface between physiology and behavior is just as complex and not well understood.

It's not that we will never find any gene that affects behavior. We have, and we will. But to draw any big picture conclusion outside the scope of those specific findings is wild and decades if not centuries early.