Bisexuality is real, and most straight women are basically lesbians, according to a study by Cornell University. Their research measured the dilation of individuals’ pupils while watching porn to establish the subject’s sexual preference. As you would expect, straight men’s pupils dilated more to images of women in states of arousal.
Bisexual men responded to both, as did supposedly heterosexual women.
“We can now finally argue that a flexible sexual desire is not simply restricted to women — some men have it, too, and it is reflected in their pupils,” co-author, Ritch C. Savin-Williams concluded. Guess those “art films” had it right all along. [Source]