Tracking a genetic link to sexuality BY FAYE FLAM Knight Ridder Newspapers Geneticist Dean Hamer says he never chose to be attracted to men. As we talked inside the renovated Washington, D.C., townhouse he shares with his partner and two dogs, the scientist popularly associated with so-called "gay genes" told me he knew he was gay since he was about 5. That's what partly motivated Hamer, 54, to switch from basic molecular genetics to studying sexual orientation in 1992. When he told his colleagues at the National Cancer Institute what he was doing, they were puzzled. "It was pretty far...