*sigh*
Yes, generally in America it's for religious reasons. I do live in America, and there are certainly some crazy-ass moms who teach kids seriously messed-up things. But public school proved a little too conformant to my parents when my brother tried it until, I wanna say 3rd grade?
Anyway, we went through a lot of things after public school and ended up with homeschooling. No-one in my family is religious in any way, and being homeschooled allows one to learn in a way that is modified by the student's learning habits and also allows you to focus on what you think you're going to end up in.
If you remain unconvinced, my friend Chelsea won several Irish harp worldwide competitions for her age (18) and now is absent at Harvard. I myself am pursuing Art and will be participating in a Model United Nations this year, and have been in a few art shows.
I like it, it's quite easy-going and usually proves for an unusually intelligent person. It certainly is not for everyone though. Lot's of people do it even though the teachers (parents) were never meant to teach children, or adults for that matter.