My mother was one of nine, although only five lived out of infancy. She also had several step brothers and sisters. My father was an only child. Both parents experienced the Depression as children, and had fathers who were alcoholics. Both parents were estranged from their families, so we had no contact with any aunts, uncles or cousins when I was a child, and only minimal contact with grandmothers (both grandfathers were deceased by the time I was born, and both grandmothers remarried).
My parents did the best they could, but they really weren't equipped to be parents at all. They had no real frame of reference for how a normal healthy family looked, and no extended family support system.