<p>Cultural, familial and peer expectations play a HUGE role.</p>
<p>For instance (granted, this is hardly scientific), I went to a highly regarded public school (which usually bested the highly regarded private school and city magnet school in the area) in an affluent town which also schooled kids from the surrounding towns (one, not as affluent, but still upper-middle class and the rest working-class towns).</p>
<p>The HS sent a lot of kids to the Ivies, Stanford, MIT, Northwestern, Duke, UChicago, etc. every year, but the overwhelming % of the kids who got admitted to those schools came from my town and the neighboring upper-middle class town, despite all of the students having access to excellent teachers, resources, tutoring, etc.</p>
<p>(Since the HS was about 99.8% white race doesnt factor in here).</p>
<p>The kids from the more affluent towns expected to go to college (if not a top one) whereas for the kids from the less affluent towns, college was an option.</p>
<p>Thats not to say genetics (tho, it could be just familial expectations) doesnt also have a role interesting enough, kids of college professors, physicians and lawyers (and other parents with advanced degrees) seemed to do better academically than the kids of affluent parents who didnt have advanced degrees.</p>