If ‘gay’ marriage is allowed, it re-opens the door for all other ‘marriages’... Man and dog - women and 500 illegal aliens - man and 20 wives... really, if the State can’t define marriage between a man and a woman - then they can’t define it... PERIOD.
Someone else pointed out a few days ago on another thread that if the definition of marriage is thrown wide open, a wealthy individual could potentially “marry” his children and avoid estate taxes. The commenter also commented that if this became a common practice, the Democrats would start pushing to return marriage to the “one man, one woman” definition.