I agree, Le Chat
I think the key thing is whether the person in charge of the family, male or female, is a good role model.
All circumstances are different. If the person "in charge" of the family unit has a strong enough personality to cope with their situation, earn a living, is honest and hardworking then the likelihood of those qualities being passed on to their family is high.
It takes a strong child to break away from a pattern of - what shall I call it? - inadequate parenting? It can be done and I have seen plenty of examples of it - children of alcoholics who realise there is more to life and so make sure it doesn't happen to them. Children who have been victims of abuse ensuring that the damaging spiral stops with them so that their children are safe.
"Inadequate parenting" is just as likely to happen in homes with two parents as it is with single parents. Let's start taking each family unit at its own value instead of lumping them all together.