Hmmm, not if they have reached age of consent which vary greatly between countries and possibly states and only if they perform said act. One kid/teenager could identify itself as hetero/bi/homo/whateversexual for example without having had sexual intercourses.

Also I haven't seen parents being jailed in the countries I have lived in because their teenager were having sex regardless of the age of consent (excluding cases where said parents were actually involved in the act).

Congratulations, you just sent the parents of heterosexual kids to jail