“…Whereas assortative mating describes systematic patterns of nonrandom mating, the adjective positive narrows it down to nonrandom mating between individuals who are similar on one or more aspects. Indications for positive assortative mating among humans have been found repeatedly in correlational research in which similarity between partners concerned factors such as religion, attitudes, and personality characteristics (Botwin, Buss, & Shackelford, 1997;Feng & Baker, 1994;Little, Burt, & Perrett, 2006;Vandenberg, 1972), and, important in the present context, physical attractiveness (Chambers, Christiansen, & Kunz, 1983;Murstein, 1972;Price & Vandenberg, 1979; for a meta-analysis, see Feingold, 1988). Positive assortative mating seems to be functional in that higher degrees of similarity are associated with higher levels of relational and marital success (Cavior & Boblett, 1972;Keller, Thiessen, & Young, 1996;Little et al, 2006;Vandenberg, 1972;White, 1980) and with greater genetic relatedness, thus facilitating inclusive fitness (Thiessen & Gregg, 1980).…”