I think it will be legalised, personally what people do in their private lives is not something I worry about but no Religious institution should be forced to hold gay marriage services as stasted previously by Ron
In the beginning God created the heavens and the earth.
Why are you so keen on increasing the birth rate? Or is it only amongst certain groups of people? Over population is going to be a huge problem for the world and no plans are in place to tackle it (outside China). We should be discouraging large families by such things as cutting off child benefit beyond two children. If there is reasonable evidence that polygamy leads to higher birth rate then that is a great reason to keep it illegal.