Yep. But it is more about skills of social life, not just about biological intellectual capabilities. Like, say, underfed and iodine-deficient western Ukrainians in 1950-60s (with all advantages of Soviet schools) were, en masse, stupidier than their well-fed brothers from Canada and USA.A person's living conditions influence them. It's one thing to grow up in freedom, but quite another to grow up in prison. Who is more likely to become a career criminal?