Psychology Child Intellectual development?

I remember having a conversation with someone about this where they were a psychology student. And they explained how a childs development can only be as strong as the X Y graph of the intellect they are surrounded by. ie a child who is surrounded by alot of intellectual adults will have greater general knowledge in comparison to a child who is influenced by less adults who cant p on as much info. Is this an actual theory? Who's theory is it? Post links plssssssssssss. Thanks