Popular theory suggests that facial averageness is preferred in a partner for genetic benefits to offspring. However, whether facial averageness is associated with genetic quality is yet to be established. Here, we computed an objective measure of facial averageness for a large sample (N = 1,823) of identical and nonidentical twins and their siblings to test two predictions from the theory that facial averageness reflects genetic quality. First, we use biometrical modelling to estimate the heritability of facial averageness, which is necessary if it reflects genetic quality. We also test for a genetic association between facial averageness and facial attractiveness. Second, we assess whether paternal age at conception (a proxy of mutation load) is associated with facial averageness and facial attractiveness. Our findings are mixed with respect to our hypotheses. While we found that facial averageness does have a genetic component, and a significant phenotypic correlation exists between facial averageness and attractiveness, we did not find a genetic correlation between facial averageness and attractiveness (therefore, we cannot say that the genes that affect facial averageness also affect facial attractiveness) and paternal age at conception was not negatively associated with facial averageness. These findings support some of the previously untested assumptions of the 'genetic benefits' account of facial averageness, but cast doubt on others.
KeywordsMate preference; physical attractiveness; good genes; mutation load; developmental stability; twins Facial averageness is thought to be attractive in a mate (Grammer & Thornhill, 1994;Komori, Kawamura, & Ishihara, 2009;Penton-Voak et al., 2001). This preference has been found across cultures (Apicella, Little, & Marlowe, 2007;Rhodes, Yoshikawa, et al., 2001) and appears to be more important than (and independent of) other traits such as facial
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Author Manuscript Author ManuscriptAuthor ManuscriptAuthor Manuscript symmetry or feature size (Baudouin & Tiberghien, 2004;Valentine, Darling, & Donnelly, 2004). However, the mechanism for this preference for facial averageness is unclear. The predominant theory is that facial averageness reflects "good genes", that is, heritable genetic quality. By mating with individuals who possess good genes the associated advantages could then be inherited by offspring, increasing the survival and/or reproduction of the offspring. As a result, individuals may have evolved to attend to cues of genetic quality, such as facial averageness, when making mate choice decisions (Gangestad & Simpson, 2000;Little, Jones, & DeBruine, 2011;Roberts & Little, 2008).Facial averageness is commonly thought to represent good genes through resistance to developmental instability, which is the sensitivity to perturbations during development (Polak, 2003). This theory stipulates that these perturbations disrupt development in random ways, which can manifest in facial development as deviations from the average face shape of the popu...