Relationships between estimated autozygosity and complex traits in the UK Biobank

<div><p>Inbreeding increases the risk of certain Mendelian disorders in humans but may also reduce fitness through its effects on complex traits and diseases. Such inbreeding depression is thought to occur due to increased homozygosity at causal variants that are recessive with respect to fitness. Until recently it has been difficult to amass large enough sample sizes to investigate the effects of inbreeding depression on complex traits using genome-wide single nucleotide polymorphism (SNP) data in population-based samples. Further, it is difficult to infer causation in analyses that relate degree of inbreeding to complex traits because confounding variables (e.g., education) may influence both the likelihood for parents to outbreed and offspring trait values. The present study used runs of homozygosity in genome-wide SNP data in up to 400,000 individuals in the UK Biobank to estimate the proportion of the autosome that exists in autozygous tracts—stretches of the genome which are identical due to a shared common ancestor. After multiple testing corrections and controlling for possible sociodemographic confounders, we found significant relationships in the predicted direction between estimated autozygosity and three of the 26 traits we investigated: age at first sexual intercourse, fluid intelligence, and forced expiratory volume in 1 second. Our findings corroborate those of several published studies. These results may imply that these traits have been associated with Darwinian fitness over evolutionary time. However, some of the autozygosity-trait relationships were attenuated after controlling for background sociodemographic characteristics, suggesting that alternative explanations for these associations have not been eliminated. Care needs to be taken in the design and interpretation of ROH studies in order to glean reliable information about the genetic architecture and evolutionary history of complex traits.</p></div

Large-scale genomics unveils the genetic architecture of psychiatric disorders

Family study results are consistent with genetic effects making substantial contributions to risk of psychiatric disorders such as schizophrenia, yet robust identification of specific genetic variants that explain variation in population risk had been disappointing until the advent of technologies that assay the entire genome in large samples. We highlight recent progress that has led to a better understanding of the number of risk variants in the population and the interaction of allele frequency and effect size. The emerging genetic architecture implies a large number of contributing loci (that is, a high genome-wide mutational target) and suggests that genetic risk of psychiatric disorders involves the combined effects of many common variants of small effect, as well as rare and de novo variants of large effect. The capture of a substantial proportion of genetic risk facilitates new study designs to investigate the combined effects of genes and the environment

Facial Trustworthiness is Associated with Heritable Aspects of Face Shape

Facial trustworthiness is thought to underlie social judgements in face perception, though it is unclear whether trustworthiness judgements are based on stable facial attributes. If this were the case, we could expect a genetic component of facial trustworthiness. From facial photographs of a large sample of identical and nonidentical twins and siblings (1320 individuals), we tested for genetic variation in facial trustworthiness and genetic covariation with several stable facial attributes, including facial attractiveness, two measures of masculinity, and facial width-to-height ratio. We found a significant genetic component of facial trustworthiness in men (but not women), and significant genetic correlations with the stable morphological facial traits of attractiveness (positive), perceived masculinity (negative), and facial width-to-height ratio (negative). However, there was no significant genetic or shared environmental correlation between facial trustworthiness and an objective masculinity score based on facial landmark coordinates, despite there being a significant phenotypic correlation. Our results suggest that heritable facial traits influence trustworthiness judgements

Assessing the accuracy of perceptions of intelligence based on heritable facial features

Perceptions of intelligence based on facial features can have a profound impact on many social situations, but findings have been mixed as to whether these judgements are accurate. Even if such perceptions were accurate, the underlying mechanism is unclear. Several possibilities have been proposed, including evolutionary explanations where certain morphological facial features are associated with fitness-related traits (including cognitive development), or that intelligence judgements are over-generalisation of cues of transitory states that can influence cognition (e.g., tiredness). Here, we attempt to identify the morphological signals that individuals use to make intelligence judgements from facial photographs. In a genetically informative sample of 1660 twins and their siblings, we measured IQ and also perceptions of intelligence based on facial photographs. We found that intelligence judgements were associated with both stable morphological facial traits (face height, interpupillary distance, and nose size) and more transitory facial cues (eyelid openness, and mouth curvature). There was a significant association between perceived intelligence and measured IQ, but of the specific facial attributes only interpupillary distance (i.e., wide-set eyes) significantly mediated this relationship. We also found evidence that perceived intelligence and measured IQ share a familial component, though we could not distinguish between genetic and shared environmental sources

No relationship between intelligence and facial attractiveness in a large, genetically informative sample

Theories in both evolutionary and social psychology suggest that a positive correlation should exist between facial attractiveness and general intelligence, and several empirical observations appear to corroborate this expectation. Using highly reliable measures of facial attractiveness and IQ in a large sample of identical and fraternal twins and their siblings, we found no evidence for a phenotypic correlation between these traits. Likewise, neither the genetic nor the environmental latent factor correlations were statistically significant. We supplemented our analyses of new data with a simple meta-analysis that found evidence of publication bias among past studies of the relationship between facial attractiveness and intelligence. In view of these results, we suggest that previously published reports may have overestimated the strength of the relationship and that the theoretical bases for the predicted attractiveness–intelligence correlation may need to be reconsidered

Facial averageness and genetic quality: testing heritability, genetic correlation with attractiveness, and the paternal age effect

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

A Warm Heart and a Clear Head

Prior studies on the association between weather and psychological changes have produced mixed results. In part, this inconsistency may be because weather's psychological effects are moderated by two important factors: the season and time spent outside. In two correlational studies and an experiment manipulating participants' time outdoors (total N = 605), pleasant weather (higher temperature or barometric pressure) was related to higher mood, better memory, and “broadened” cognitive style during the spring as time spent outside increased. The same relationships between mood and weather were not observed during other times of year, and indeed hotter weather was associated with lower mood in the summer. These results are consistent with findings on seasonal affective disorder, and suggest that pleasant weather improves mood and broadens cognition in the spring because people have been deprived of such weather during the winter.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73377/1/j.1467-9280.2005.01602.x.pd