[jmacusa]

So how is this any different than one man having four wives? Can one woman now have four husbands? Will someday it be legal to marry your sister? Where does it end?

[a fool in paradise]

Coming soon to schools, “Heather has 3 mommies and a psychiatrist”

[DuncanWaring]

So how is this any different than one man having four wives?

Well, for a start, there's at least one male and at least one female; they can produce offspring without outside assistance, which is ultimately the whole purpose of marriage.