Performance on tests also influenced by pollen count in the air on the day of testing for people with sinus trouble.
Going hardline on the nature/nurture debate is ridiculous.
For every nature (genes) study, there’s context/environment/parenting/society (nurture) study….
To put it bluntly, their dicks are the same length and I wish people would stop pulling down everybody’s pants and checking. It’s both. Nobody has ever been raised in a vacuum to find out otherwise.