Having a brother can influence a woman's impression of men's looks. For a study led by Lisa M. DeBruine, a psychologist at the University of Aberdeen in Scotland, researchers showed 156 women pairs of faces of men and women who were close in age to the participants and asked them to click on images they found more attractive or more trustworthy. The viewers did not know that one of the faces in each pair had been digitally altered to have characteristics in common with their own. The participants who had brothers generally rated men whose faces looked like their own to be a turnoff, and the effect increased the more brothers a woman had. Experience with a brother heightens women's avoidance of potential mates who look like they might be kin—a means of preventing inbreeding, DeBruine says. But when people see a man or woman who resembles them—perhaps suggesting a familial bond—they're more likely to perceive that person as being trustworthy, this study and other research shows.