An article in the LA Times examines the search for physical traits by which one can identify sexual orientation:

 Studies contradict each other, and some promising paths don’t pan out. (A link between male homosexuality and finger lengthsisn’t holding up, and a claim that gays have distinctive fingerprint ridge patterns is largely discredited.) Scientists don’t always agree on how to interpret the results, and more progress has been made with regard to men than to women.

• “Scientists Link Brain Symmetry, Sexual Orientation” Via Wired.com: Using MRI scans of gay and straight...
• “Gay Unions Shed Light on Gender in Marriage” From Nytimes.com: “Notably, same-sex relationships, whether between men or women,...