It sounds like your argument is that the ability to become an engineer or physicist is an in-born trait, which no amount of study and work can overcome, which sounds absurd to me.

As the high school coach used to say: "You don't need talent to practice!"

Barring people truly born with mental disabilities, anyone can do it with the right attitude and resources. I'd be less worried about the gene pool and more worried about the unequal distribution of education spending causing pockets of the country to be financially unable to educate people.