If you read "Why Nerds Are Unpopular", [0] then look at these photos by pg, [1] and then ask yourself, "who is in the chess club?" then "who is the in the weight lifting/track team?"

    "The kind of things we were interested 
    in didn't count for much in our high school." -- pg

Having gone to HS around about the same time and a mathlete, I recognise similar dynamics, even though I was 10,000 Ml away. It's no myth.

[0] http://paulgraham.com/nerds.html

[1] http://paulgraham.com/gateway.html

It was at my school. Our jocks and nerds were very intermixed and hung out together in different groups, and our cheerleaders were mostly losers. The "popular" girls didn't really do any sports or activities to speak of, except for some resume-padding stuff like Key Club.

At other schools, I honestly think the stereotypes in movies became self-fulfilling prophecies. The terminology came from movies, and perhaps some of the division did as well.