It's usually evolution or sex or race or something like that.

One of my friends was home schooled. It was at least partly about religious values, but I think it was also partly about him being a bit of a strange kid and getting along better at home. He went back to public schools in middle school, and that was real rough but I think he was happy by the time he got to high school.

I'm sure there are many reasons to home school, but the one I hear about most is religious.