if its protective sex then you shouldn't be mad. yes it sucks that they're having sex when they're young but what would you rather have, you telling them no and and them doing it anyways or you telling them use birth control and a condom and them doing it. my moms philosophy was i know i can't fight you on sex because if you want to do something you're going to do it no matter what i say, and i'd rather you tell me about it so i can keep you protected instead of you having a baby. if you're mad at them over this they probably will be more sneaky and more irresponsible, but if you talk to them about and keep sex information open you can be sure they are being safe.