NotNew,
Researchers conduct these studies by measuring responses to images, etc., such as pupil dilation, respiration and heart rates and of course genitalia response. As for the rest of your comments, these have been addressed in detail previously on this site. Why would you think we wouldn't reproduce? Gays want and have children now, and science is rarely involved. Have you heard of surrogates? Humans would work all of that out. Please research the previous OPs on this.