It's also possible that someone you know will decide to tell you that all the nursery rhymes you learned as a kid were about either a) syphilis or b) the Black Death.
And of course, they're right. The stories and songs we use to entertain children are grounded in an awareness of nightmares and horrors. Magical fables and singable rhymes developed out of real-life catastrophes and plagues. How exciting it is to realize that our generation is also producing such rich fodder for future folklore!
Just this week, I heard about something that sounds like an actual horrible fairy-tale come to life and/or inspiration for a horrible fairy-tale still to be written. Katya Adler of the BBC reports that in Spain, over a period of forty-fifty years (from Franco to the 1990s), an estimated 300,000 children were stolen from their parents by doctors and nurses and nuns and priests and then sold to new families. The birth parents were told their children had died. Initially, babies were taken from ideologically unacceptable homes (i.e. homes that housed people who didn't like Franco) and given to Franco loyalists; later, babies were taken from morally unacceptable homes and redistributed to morally upstanding would-be parents; later still, babies were taken from poor people mostly because money could be made by selling them to rich people.
Many of the graves of infants said to have died have since been discovered to contain stones or adult corpses.
The government, adhering to an amnesty law in place since the transition from Franco's regime, has refused to set up a formal inquiry into this clergy-backed child trafficking.
It might not be reasonable to fear that malevolent fairy will snatch your child, but in pretty-near-contemporary Spain, it turns out it was completely reasonable to fear that a nun would steal your baby.