"children's development is the end of a much longer process that involves many complex decisions by parents, one of which is how many children they should have and how much love and care they should lavish on each. But even before they get to this stage, the parents must agree to choose each other as mates. It's probably fair to say that these are the two biggest decisions that we make in our lives".
Evolutionary Psychology (2005)
R. Dunbar, L. Barret & J. Lycett