I had 3 siblings and as a teen remember feeling isolated and alone much of the time. I think that parents have a responsibility to help their children find a passion or activities to keep them busy and social - only children or not!
I don’t recall.
Perhaps the good Doc can recall statistics better than I on such matters.
—do only children end up in trouble statistically more often than those with siblings.
My best guess is that
that issue
is a lesser discrimminating variable.
PARENTING is the KEY variable.
However, all other things held equal . . . I don’t know. Great question.