TIME's Mark Benjamin points out some passages from a 2008 Rick Perry book in which he compares homosexuality to alcoholism:
…in a little-noticed passage in his first book, “On My Honor,” a encomium on the Boy Scouts published in 2008, Perry also drew a parallel between homosexuality and alcoholism. “Even if an alcoholic is powerless over alcohol once it enters his body, he still makes a choice to drink,” he wrote. “And, even if someone is attracted to a person of the same sex, he or she still makes a choice to engage in sexual activity with someone of the same gender.”
He also said that gays should not have sex:
In “On My Honor,” Perry also punted on the exact origins of homosexuality. He wrote that he is “no expert on the ‘nature versus nurture’ debate,” but that gays should simply choose abstinence.
Think Progress offers the full passage if you're interested in checking it out.