Gaydar

The January 2008 study investigated people's ability to identify homosexual men from pictures of their faces alone. In an initial experiment, researchers Nicholas Ruleand Nalini Ambady from Tufts University perused online dating sites and carefully selected 45 straight male faces and 45 gay male faces.

http://www.scientificamerican.com/article.cfm?id=something-queer-about-that-face