There was an experience the researchers did, I forgot the details but shortly it was a study about a comparison between the reactions that guys and women had, when they saw the same sex and the opposite sex of theirs, and how strong the reactions were. First they put a group of people inside a glass room and there was another group outside watching them. So they brought group of men to look at the group who were inside( men and women). The second experience they put women and they did (the same process). The interesting thing is men observers have shown a very strong reaction for the sex that  they are attracted to, and they gave, just an average reaction  toward the other sex, nothing more. Now about women observers, funny, most of them, they gave the same strong level of reaction for both sex, and the reason behind that is women in general have a very high sense of competition and want to compare whose prettier when they see other women. And why I brought this subject? A woman on the street remind me about it.