LGBT movements are opposed by a variety of individuals and organizations. They may have a personal, political or religious prejudice to gay rights, homosexual relations or gay people. Opponents say same-sex relationships are not marriages, that legalization of same-sex marriage will open the door for the legalization of polygamy, that it is unnatural and that it encourages unhealthy behavior. Some social conservatives believe that all sexual relationships with people other than an opposite-sex spouse undermines the traditional family and that children should be reared in homes with both a father and a mother. As society in some countries (mostly in West Europe, North America,Australia,New Zealand,Japan,Taiwan and South Korea) has become more accepting of homosexuality, there therefore has also been the emergence of many groups that desire to end homosexuality; during the 1990s, one of the best known groups that was established with this goal is the ex-gay movement.