yea im with the other here.
If you and your wife are good parents, the issue of sex, whilst daunting will be reasonably easily managed.
Karl you seem like a pretty decent dad, trust that you've brought your daughter up with ability to make her own choices and trust that they will be the right one's for her. Naturally you'll try and be protective, just dont over do, otherwise you risk her using that as avenue of rebellion. And make sure she keeps focusing on school work, coming into 15-16 years old, not a lot of boys will hang around the study nerd looking for a bit when there is loads of other attractive girls, who are happy to party it up and sleep around.
If she's focused on school and furthering her education, more than half your battle is won.