It seems to me the boy got off lightly by only being handcuffed. Unless the father if the girl clamped the handcuffs on a part of the boy not used to being shackled in such a manner.
Regardless, I hear a lot about kids reaching puberty faster these days. That's utter nonsense. At the beginning of the last century if you were not married and pregnant with your first child by the age of 13, you were considered an 'old maid'. Granted, you weren't expected to live much past 30 either, but 100 years isn't a huge ammt of time when you are talking about evolution, either.
Don't be so quick to pass judgement om the boy being the only 'guilty' party in this situation either. There is a lot of pressure on teen girls to dress, act, and be a certain way nowdays. It's all the rage to have a Baby Daddy. Maybe she was just trying to fit in. And we all know how much pressure there is to do that, at that age.
Incidentally the age of consent in most states is 16. That's the age the law recognizes as someone being able to have the understanding of the consequences of having sex. If a 15 year old and a 14 year old are trying to do the nasty, anything short of killing them to keep them from having sex should be protected under the law.