A few years ago I had four high school history classes- two high-level (college prep), two low-level (remedial). I was curious whether there was any commonality, and I had a little time to kill.
The kids had filled out information cards, and I began to hand-sort them. 

Maybe zip codes, which could be class? Nope, no pattern.

The Lou Dobbs Effect? Ethnicity? No, that wasn't it.

Astrology?- Birthdays? No.

And then I had an idea. I created two piles. One was for kids who had listed as their guardian a male with the same last name. The other pile was everyone else.

And presto. That pile was my top classes, with one exception. The other pile was my low-achievers, again with one exception.

But the first exception was arrested in the winter and left school; the second was a Down Syndrome kid, who was flourishing despite that.

I post this with no conclusion drawn. Just an anecdote.

Happy Father's Day.