Redefine Marriage

Call me old fashioned, but in my opinion the states are messing with the family unit too much when they started redefining marriage. However, since the federal government failed to define marriage by law, it has obviously come under the category of "states rights." In some states two men or two woman can be married to each other by law, whereas it was illegal in the past. Why not carry the trend a bit further than it is going now? How about bigamy. Lots of people would like to have more than one wife legally, or possibly even more than one husband. Why couldn't a state legalize bigamy? Or, how about moving legal marrying age to age 12 or 13. As long as we're redefining marriage, why not? Here's an even more interesting idea. How about letting each family write their own marraige contract expressing what kind of marraige they want their family to have, and registering it with the state, and then do what they want for their family. Potentially, anyone of legal age could make up their own definition of marriage, register it with the state and go live in marital bliss. I think messing with the institution of marraige and the family is a recipe for disaster in our society. What do you think?