My uncle through my mom's second marriage used to always want the littler girls to sit on his lap and he'd bounce them up and down, in the basement TV room when none of the other adults were around. Years later, when his own two daughters were married and had kids of their own, it came out that he sexually abused his daughters when they were kids.

That guy always gave me the creeps anyway. Glad I was 16-17 at the time and out of his preferred age range.