Cheryl Morgan has written some wise words in her blog about polygamy and other things related to marriage and the government. Her post was triggered by some comments published in the Guardian. The comments deal with more that simple UK issues.
As Cheryl points out these are big and important issues about how people organize theirs lives and we have the frightful actions of various religious factions trying to use the government to enforce their views on morality and social institutions on everyone else. I highly recommend reading what Cheryl has written. A few months ago I wrote a short piece covering similar issues.