[chub500]

I think it makes most sense if you see it from the perspective of your child. Having family and friends "witness" your marriage ceremony (especially your vows) has a strong cultural pull toward monogamy to the benefit of raising your children in a two parent household. Apparently the government saw this commitment so valuable they tied into it legislatively.

[HeyLaughingBoy]

Our child witnessed us getting married. He liked it so much that he asked if we could get married again a week later.