I believe it, not because I have (yet) experienced it directly but because given the family lives of some of the kids I teach I can easily see how it could arise. Yes, these are family lives I would have found hard to imagine had I stayed in my first career as middle management in a multinational company, and just came into contact with my own children and friends from families in my own area. However, though these lives are hard to imagine, it doesn't mean that they don't exist...
Very large families, born to very young women / girls from different fathers, living as extended multi-generational groups in which few if any of the adults are fully literate or have any kind of qualification, where older kids look after younger ones and where grandmothers look after the children of their daughters as if they were their own, where kids 'play out' in packs and fall asleep in whichever house and whichever bed they might find themselves near at midnight, and where if the kids are noticed at all as individuals it will be as a 'hey you' accompanied by a slap around the ear ... neither the Daily Mail nor the Telegraph has invented these families I can assure you ....