As all parties agree, many same-sex couples provide loving and nurturing homes to their children, whether biological or adopted. ... Excluding same-sex couples from marriage thus conflicts with a central premise of the right to marry. Without the recognition, stability, and predictability marriage offers, their children suffer the stigma of knowing their families are somehow lesser. They also suffer the significant material costs of being raised by unmarried parents, relegated through no fault of their own to a more difficult and uncertain family life. The marriage laws at issue here thus harm and humiliate the children of same-sex couples.