It can be the result of unfortunate sexual experimentation, or maybe a reaction caused by emotional, physical or sexual assault or neglect. Some display this behaviour after having been shown or seen a lot of pornography, or after adults have had sexual intercourse in front of them. Others are more impulsive in their actions, with no apparent instigator or premeditative planning.
The problematic or harmful sexual behaviour is often only one of several issues (behavioural issues, psychological or neurological problems) the adolescent is dealing with, and must be understood as such; in context, rather than as “its own thing”. There are, however, a significant percentage of adolescents not otherwise troubled, and whose cognitive and social functions fall within the normal part of the spectrum.