The Essentialist Argument and Nature

One of the standard arguments against homosexuality goes: "It's contrary to our nature, considering there's no way to reproduce, so of course it's wrong." While one of the arguments in support of homosexuality goes "It's genetically determined, so it's part of our nature and it's right." (the essentialist argument).

What I find interesting is that they both use the same premise, "If something is natural, it is good." Whether homosexuality is genetically determined or not, the rebuttal against the pro-homosexual will normally include mention of the evils of other natural tendencies (like kleptomania). What the anti-homosexual doesn't realize is that they are undermining their own argument as well!