I have known people who have child after child casually with no thought of how they will look after them. Who make no effort to bring them up at all, just feed them and hope it will work out. I'm old enough that I have seen that next generation begin to do the same thing. What other example do they have to live by? There is no doubt that they exist. Many are not single parent families exactly, Some are unmarried. (and in fact there are no single parents unless a sperm donor was used - the father is just not around to help)
The ones I have known were mostly on benefits, but that's partly because of my own social class. An unmarried woman with money for a nanny and boarding school would not be seen the same way anyway.
They mostly (in my experience) live on estates surrounded by others with no hope for the future. They may not know anyone who has a job, let alone work themselves.
However it came about we need to do something about it.
It's been suggested to me that one way forward is to break the cycle by breaking up estates. Mixing poorer/unemployed people in with those who are better off instead of hiding them away. Imagine if you put each such family in a house on a street where most people clean their cars, weed their gardens and go to work.
I can imagine people cringing already and yes some might cause some problems, but humans respond to peer pressure. We have a need to fit in with others. It's a bit simplistic to say that they will see others cleaning their windows and start doing theirs, but there is some truth in it. On a council estate it feels like there is no point in trying and you're surrounded by others who feel the same way.
Given a fresh start and surrounded by people who have found ways to improve their lives might just do the trick.