There have been a raft of warnings circulating on Facebook for years (but seem to have had a recent uptick) warning that memes that are shared on social media that encourage people to post trivia about their background or childhood actually have an ulterior motive - they allow criminals to collect useful information about you to get past security questions, for social engineering and for password hints.
Here is one example from Crime-Stoppers Victoria's Facebook page:
PSA: Just. Stop. Posting. Reponses to this crap. It's social engineering. They are designed to get password hints, among other things. Tell your friends, too. And their friends.
I think these claims sound unlikely. Are there cases of criminals using such techniques on social media?