Akenaton is full of shite.
In fact, gay marriage bans INCREASE the rate of STDS.
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...Using micro-and state-level data, we find evidence that same-sex marriage bans reduced tolerance for gays and increased the syphilis rate, a rough proxy for risky homosexual behavior. However, we find no consistent evidence that same-sex marriage bans impacted risky heterosexual behavior,marriage, or divorce.
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Full peer-reviewed paper here (no paywall):

http://www.academia.edu/446302/The_Effects_of_Same-Sex_Marriage_Laws_on_Public_Health_and_Welfare