FILE - In this Aug. 20, 2007, file photo, Julio Cabrera poses in a local park in Chicago. Cabrera and his brother Mauricio, of Fort Worth, Texas, are among almost 800 gay brothers nationwide who donated blood or saliva to help scientists search for genetic clues about the origins of homosexuality. Both are convinced their sexual orientation is as deeply rooted as their Mexican heritage. The research suggests a possible genetic link to homosexuality but the results aren¿t proof. (AP Photo/M. Spencer Green, File)