tough question. You know your daughter best, the peer group, and the boy. I would get to know the boy and his family as a priority. He is legally an adult. Some sexual behavior could be considered rape. Have a long talk with your daughter about dating an adult. Probably not a good idea. However, you know this situation best.
Discuss this with her, the boy, families and perhaps an outside source such as your pediatrician who may know both parties.
Wayne Yankus, MD, FAAP
expert panelist: pediatrics
I think it is ill-advised, assuming the 15 year old is a girl. There is a lot of maturity difference between early teens and young adults. This is a difficult situation to negotiate and I hope you and your child have a solid relationship and mutual trust. Good luck.