Of course children do better when they have the love and support of more than one person, particularly when that has economic implications, but there is no evidence that this needs to be a father. Grandparents, aunts and uncles, friends, etc., are fine. For most of human history, this is how humans survived - with alloparenting from relations and "as kin". The importance of the nuclear family (with a heterosexual married couple) as vital, is a myth coming out of patriarchy in the past few thousand years at best.