Not family pics per se, but. . .
My first wife and I had nude pics of ourselves. Full frontals, close-ups, singles, duos. We sometimes brought them out during sex. You might call them homegrown porn. We kept them in an envelope at the back of a drawer in the bedside table.
Soon after we got divorced, she remarried. She said he looked a lot like me. The only similarity I could see was that he had dark hair. I was sure I was a lot better looking!
One night I did emergency babysitting for them of our son. Just after he'd gone to bed the phone rang. The nearest phone was on their bedside table, so I took it there. After I told the caller they were out, some curious part of my brain wondered whether she still kept our pics in the drawer. I looked inside and, lo and behold! there was the old envelope -- but now noticeably thicker. I guiltily opened it and there were our pics, now supplemented with pics of her and her new husband. She had dated him before we got married, so I new he was hung, but was unprepared for the graphic evidence. He was easily twice my length and lots lots thicker. Some of his pics were intermingled with mine, implying there was some comparing going on. It was definitely hot thinking they used those pics in the same way she and I had and gotten off over them.