If that's what it takes to do what's right, then yes: change the constitution to prohibit marriage to a person of the same gender. And while at it, specify that a man cannot marry an under age child, nor a near relative, nor any woman who is already married, nor can he if he is already married, nor can he marry any other than a human being. It seems common sense, but the way things are changing it won't be long before such specifics are necessary. We all have the right to marry a person of the opposite sex, who is of age to consent, who is not a near relative, who is not already married, if we are not already married. The LGBT have the same rights already.