teenage girls

what is it with the young teenage girls of today, twelvies as they are now known, there seem to be a percentage that are all about make-up, flashing their boobs, and getting it on with boys, (some years older) and yeah i mean 12 year olds going all the way, and then there is another percentage the for some fucked up reason sit back and are jealous and envious of the other group and just pretend to be dumb ditsy morons to cover up the fact they have half a brain! Surely there is still the group of half decent guys that want to be with a smart girl, that has intelligence and doesnt laugh at really inappropriate or just plain not funny times, and one that has self respect and not throws herself at every boy that comes near, how do we as mothers make our daughters understand its ok to be the smart one, the one that is uninterested in swapping spit in the playground, that enjoys doing her homework and having friends and a normal sense of humour? i know i keep telling me its ok to be who you are and never pretend to be someone you arent to make someone else happy especially if it means lowering your standards and respect, and while at the age of 12 im satisfied that she is listening and taking things on board and disgusted in the girls swapping spit, flashing their boobs and going all the way, how much longer is it going to last before she turns into one of those girls she now sneers at? please tell me it will be forever lol she will be a good girl and study hard and worry about boys when she is in her 20's and ready to find a husband lol yeah yeah i know but for now i'll keep dreaming