One shibboleth of much of the Religious Right is the notion that sexual orientation is a choice. If that was the case, I think it would be probable human beings would not be involuntarily influenced as the subjects in the study cited below were. The study would seem to indicate that human beings have only limited control over what they as individuals find sexually attractive.
"Erotic Images Entice Even When Invisible," by Ker Than of LiveScience.com, October 24, 2006:
The use of scantily clad models in ads for everything from underwear to ice cream attest to the persuasive power of sex, but a surprising new study finds that our actions can be swayed by erotic images even when they don't consciously register in our awareness.
In an experiment, 40 men and women were shown erotic images that had been manipulated to bypass conscious detection. The participants consisted of both heterosexual and homosexual individuals.
Subjects were then shown a small "probe" pattern and asked to determine its orientation—clockwise or counterclockwise. The researchers found that subjects identified the probe pattern more accurately when it appeared where the erotic images had been, suggesting that the invisible images exerted an effect on their spatial attentions.
In general, the erotic images attracted or repelled attention depending on the gender of the nude model and also the sexual orientation of the subject. For example, heterosexual males tended to perform better on the pattern task when it followed the presentation of an invisible female nude than a male nude. Gay males, in contrast, showed more enhanced performance when exposed to invisible male nudes compared to female nudes.
"We didn't predict that," study team member Sheng He of the University of Minnesota told LiveScience. "We just wanted to see if invisible images can attract your attention or not."
The finding is detailed online in the Oct. 23 issue of the journal for the Proceedings of the National Academy of Sciences.