If we measure by the number of people directly affected, it is no contest. Estimates of the percentage of the U.S. population that is gay range between 2 and 4%. This leaves 96 to 98% heterosexuals, most of whom, seem to be devaluing or completely disregarding the value of marriage.
The largest threat to our society and to our economy is not the way people define marriage but how enthusiastically and committedly they participate in it. Sadly, particularly among the Millennial generation, fewer and fewer get married while more and more choose the lower-commitment option of cohabitation.