Thank you for contacting Just Answer. I am sorry to hear about this. Good question. The problem is with the parents. Your boyfriend was 12 years old. The sister was 15. The sister most certainly should have known better. There is certainly something the parents did here to even create such a situation.Did the parents ever try to investigate who started the sexual encounter between them. I'm just thinking, not necessarily that this is so because obviously I don't know the facts but if a 12 year old boy approached a 15 year old girl, one would think that if the 15 year old girl did not want to have sex and/also knew it was not normal she would have pushed him away. So for the parents to send him to a group home without exploring this in great detail is most especially negligent. Also, what parent wouldn't insist on their daughter having an abortion if their daughter is carrying her brother's child. Incredible!!! So where is that child now? That child would now be 25 years old. What does that child know? So to answer your question --- and I quote you, "Why would they have sex so young and is their some weird sexual lust between them?" ---- there is so much here that is so...ooo complicated. I wouldn't say there is weird lust now. I would say that the 15 year old was curious about sex and the 12 year old, your boyfriend, just, just entering puberty was lured into it by the 15 year old because, as I already said, if the sister didn't want this to happen if your boyfriend was the one to start it, the sister would have pushed him away. These parents have created a terrible mess by sending him to a group home instead of investigating all this further and getting these kids help.
Just checking to see if you have added anything to this chat. Will check back later.