Today's American family isn't what it used to be. The days of "Leave It to Beaver" have been replaced with "Modern Family," a more accurate representation of home life. The nuclear family, the blended family, and the family with same sex-parents are equally visible, loving, funny and messy.
The notion that the traditional two-parent family is not only the best, but the only, way to raise healthy children is a notion perpetuated by those fearful of losing their privileged status upheld by their virulent defense of so-called family values.
The simple truth is, children who are generously loved, esteemed, and respected do better in life than those who are not. It's not the family structure that matters, but how we treat our children. Do two wonderful parental figures provide a child with more of this than one? Sure. Do three provide more than two? Yes. And how about four? Why not? In most of the world, childrearing happens within the context of a large extended family with many members influencing a child's development and helping out in different ways.