if society is living a normal life, do normal when the family is a couple of spouses and their relatives in the ascending and descending lines that do not live in separate families. A normal family exists in the present period of history for the reproduction of mankind, i.e. for the birth and upbringing of children, and therefore should include three or four generations of relatives of at least one branch, living together in one house. It is necessary that the child saw in all circumstances, all the future ages of life and properly comprehended before he enters in each of them.
The destruction of the family both my own and someone else's, especially if the family already has children and they have not yet reached the age of majority, is a sin, except in those cases where one or both parents chose the way explicit порока1 and involve their children.
And if society does not live a normal life, then families break out of selfishness or carelessness of parents, and in society many children deprived of what needs to pour out upon them male or female hypostasis of the person, then? - Because children, after receiving flawed education in single-parent families, which in most cases is not able to give proper education, the next generation will give rise to flawed society, be chargeable with the problems of posterity.