I’m saying with no uncertainty that the portion of Mexicans that come here illegally, in general, do not represent the best genetics that Mexico has to offer in terms of academic intelligence. That is one factor (among many factors) that explains the substandard performance of Mexican American children in US schools and universities relative to other groups/races.
Of course genetics play a role in academic ability. Anyone who denies that is living in a politically correct cave. Whether you want to extrapolate that to entire groups, races, etc. then you open up the age old argument of DNA influence vs. cultural influence.