Intelligence (g) is highly hereditable on the right hand side of the bell curve. Where non-shared environment (there is no measurable shared environmental compo

Intelligence (g) is highly hereditable on the right hand side of the bell curve. Where non-shared environment (there is no measurable shared environmental component to g) is on the left hand side where people can end up with a g below their genetic potential. Basically it is relatively easy for the environment to push an individual below their potential, but near impossible to pull them above once a basic minimum is met.