When all is said and done, if one set of parents - the girl’s, in this case - is upset about these episodes, then that becomes the default position. In that event, the boy’s parents need to make perfectly clear to him that this behavior is not to happen again and make equally clear that if it does there will be meaningful consequences.
They should also require that he apologize to his cousin in front of both sets of parents and promise her that it won’t happen again. Their low rating of the seriousness of these episodes isn’t relevant. They should take this approach out of respect for the girl’s parents.
Adults need to stick together in matters of this sort.
Visit family psychologist John Rosemond’s website at www.johnrosemond.com.