These children do not know how an adult male should behave because they rarely see one. The other problem in this regard is authority. Whatever else fathers do, they establish and administer authority within the family. The fact is, it does make a difference in court whether there is a father in the family. Now, the father's role is no more important than a mother's role.
History demonstrates that fathers have been periodically been absent in the lives of their children.
But mothers have been the constant. You may not have a father, but you always have a mother. At least mothers seemed more present or durable in the lives of children. The more recent phenomenon is that as fathers continue to disappear, mothers have also begun to disappear. At the very least mom is at work, and children are left to other role models while they grow.