DH is practicing being the tough guy on his 16yo sister, so that he's ready for DD.

There are alot of factors involved, its not necessarily how you parent, although thats a big thing too. Its the child's personality, so if they follow the crowd or if they're strong enough to say no in front of their peers. I've worked in a disadvantaged school, and it also comes down to the girls just looking for some love and affection coz they might not get it at home, but then they look for it in the wrong place (such as a year 9 girl going out with a year 12). Or else having babies and getting benefits is all they know. Probably a bit of a generalisation, I'm sure.

Another thing is I hate some of the fashion for young girls - its too hooker-ish in some cases! A friends 13yo had her primary school graduation, and whilst she had a gorgeous dress that was suitable for her age, while still being fashionable, some of the girls were dressed way too old - one girl in particular had a tight red dress and bright red lipstick that was better suited to a night of seduction for a much older woman than a little girl (and really, at 13 they're still little!)