Argument: Homosexuals are born gay, have no choice
Ted Olson. "The conservative case for gay marriage." Newsweek. January 12, 2010: "Science has taught us, even if history has not, that gays and lesbians do not choose to be homosexual any more than the rest of us choose to be heterosexual. To a very large extent, these characteristics are immutable, like being left-handed."
"Let them wed." Economist. January 4th, 1996: "Homosexuals need emotional and economic stability no less than heterosexuals—and society surely benefits when they have it. “Then let them 'unchoose' homosexuality and marry someone of the opposite sex,” was the old answer. Today that reply is untenable. Homosexuals do not choose their condition; indeed, they often try desperately hard, sometimes to the point of suicide, to avoid it. However, they are less and less willing either to hide or to lead lives of celibacy. For society, the real choice is between homosexual marriage and homosexual alienation. No social interest is served by choosing the latter."
Scott Bidstrup. "Gay Marriage: The Arguments and the Motives": "Many of the reasons offered for opposing gay marriage are based on the assumption that gays have a choice in who they can feel attracted to, and the reality is quite different. Many people actually believe that gays could simply choose to be heterosexual if they wished. But the reality is that very few do have a choice -- any more than very few heterosexuals could choose which sex to find themselves attracted to."