Ok, my kids aren't quite old enough yet, but I still really enjoy this forum.
Anyway, I was thinking of having approximately the same "rules" for my kids that my mom had for me and my brothers. Group "dates", like a bunch of boys and girls going to the movies or the mall or wherever, around 13-14, and one-on-one dating around 16ish. Subject to review of course, depending on the maturity of my children and their boy/girlfriends.
I think 15 is definitely a reasonable time to be interested in the opposite sex. I'd prefer my kids not have really serious relationships at that age, but I doubt I'd outright forbid it. I went to Catholic schools until college, so we're talking pretty conservative, and it seems most of the parents had rules like mine. I don't think I knew anyone who wasn't allowed to date at all until 17 or 18. So no, I don't think it's "normal" for mainstream to fairly conservative areas. But different people have different beliefs and whatnot, so..........who knows? Maybe this IS normal for these kids' families.