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.

中文翻译：

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面部平均水平和遗传质量：测试遗传力，具有吸引力的遗传相关性以及父系年龄效应。

流行的理论表明，在获得伴侣后代遗传利益方面，优先选择面部平均。然而，面部平均水平是否与遗传质量相关尚待确定。在这里，我们计算了一个大样本（N = 1,823）相同和不相同的双胞胎及其兄弟姐妹的面部平均水平的客观度量，以检验基于面部平均水平反映遗传质量的理论的两个预测。首先，我们使用生物特征识别模型来估算面部平均水平的遗传力，如果它能反映遗传质量，则是必不可少的。我们还测试了面部平均水平和面部吸引力之间的遗传关联。其次，我们评估受孕时的父亲年龄（突变负荷的代表）是否与面部平均水平和面部吸引力相关。关于我们的假设，我们的发现是混杂的。尽管我们发现面部平均度确实具有遗传成分，并且面部平均度和吸引力之间存在显着的表型相关性，但我们并未发现面部平均度和吸引力之间存在遗传相关性（因此，我们不能说影响面部平均度的基因也影响面部吸引力），并且受孕时的父亲年龄与面部平均水平没有负相关。这些发现支持了一些以前未经检验的关于面部平均的“遗传益处”解释的假设，但对其他假设却产生了怀疑。我们没有发现面部平均水平和吸引力之间存在遗传相关性（因此，我们不能说影响面部平均程度的基因也会影响面部吸引力），并且受孕时的父亲年龄与面部平均程度没有负相关。这些发现支持了一些以前未经检验的关于面部平均的“遗传益处”解释的假设，但对其他假设却产生了怀疑。我们没有发现面部平均水平和吸引力之间存在遗传相关性（因此，我们不能说影响面部平均程度的基因也会影响面部吸引力），并且受孕时的父亲年龄与面部平均程度没有负相关。这些发现支持了一些以前未经检验的关于面部平均的“遗传益处”解释的假设，但对其他假设却产生了怀疑。