Yes. A child's environment (social stability, economic, opportunity, attitudes towards education) is key for how well-prepared s/he is for college work (particularly for someone aiming for an academic position). Because of their limited opportunities before college, they have to work much harder in their major as well as in electives courses.

It's far from heart-breaking to hear the privileged grumble about such successes. In the system as it exists, only the extremely talented from poor, or racist, or rural environments stand a chance.