[mtdewcmu]

I think your point was that cool kids and nerds are heterogenous groups, i.e. kids could end up in the same category for vastly different reasons. I agree. Practically all social science research suffers from the problem that it can't define the thing it's trying to study. They don't even try to solve problems like defining happiness or coolness. They hope that the numbers the experiments generate will look persuasive and make the exercise look like it was worth doing.

However, they isolated two groups according to some criteria, and they found that it correlated with something objective later in life. So you can speculate on other explanations, and my opinion is that the kids they called cool were troubled and rebelled because the adults in their lives were not dependable. The kids they called nerds were nerds because they followed rules and didn't rebel. They followed rules because the adults in their lives came through on promises and made it seem worth it to work and have faith that you'll get rewarded eventually.