A test of the facultative calibration/reactive heritability model of extraversion.

A model proposed by Lukaszewski and Roney (2011) suggests that each individual's level of extraversion is calibrated to other traits that predict the success of an extraverted behavioural strategy. Under 'facultative calibration', extraversion is not directly heritable, but rather exhibits heritability through its calibration to directly heritable traits ("reactive heritability"). The current study uses biometrical modelling of 1659 identical and non-identical twins and their siblings to assess whether the genetic variation in extraversion is calibrated to variation in facial attractiveness, intelligence, height in men and body mass index (BMI) in women.

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 ( = 1,823) of identical and nonidentical twins and their siblings to test two predictions from the theory that facial averageness reflects genetic quality.

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.

Genetic factors that increase male facial masculinity decrease facial attractiveness of female relatives.

For women, choosing a facially masculine man as a mate is thought to confer genetic benefits to offspring. Crucial assumptions of this hypothesis have not been adequately tested. It has been assumed that variation in facial masculinity is due to genetic variation and that genetic factors that increase male facial masculinity do not increase facial masculinity in female relatives.

Estimating the sex-specific effects of genes on facial attractiveness and sexual dimorphism.

Human facial attractiveness and facial sexual dimorphism (masculinity-femininity) are important facets of mate choice and are hypothesized to honestly advertise genetic quality. However, it is unclear whether genes influencing facial attractiveness and masculinity-femininity have similar, opposing, or independent effects across sex, and the heritability of these phenotypes is poorly characterized. To investigate these issues, we assessed facial attractiveness and facial masculinity-femininity in the largest genetically informative sample (n = 1,580 same- and opposite-sex twin pairs and siblings) to assess these questions to date.