Though many arguments against gay marriage are based in homophobia, even people who otherwise support the rights of gays and lesbians have advanced arguments against gay marriage. One main concern is that allowing two people of the same sex to marry will devalue the concept of marriage. Those against gay marriage argue that marriage is between one man and one woman and allowing gay marriage would destroy the traditional family, which defenders of this idea value.
Others argue that marriages are for procreation. This argument is related to the idea that same-sex couples are not appropriate parents and shouldn't be allowed to assume a family structure. Those against gay marriage often bring up the above points, although their arguments are based on an idea that homosexuality is morally wrong.