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. The heritability was ~0.50–0.70 for attractiveness and ~0.40–0.50 for facial masculinity–femininity, indicating that, despite ostensible selection on genes influencing these traits, substantial genetic variation persists in both. Importantly, we found evidence for intralocus sexual conflict, whereby alleles that increase masculinity in males have the same effect in females. Additionally, genetic influences on attractiveness were shared across the sexes, suggesting that attractive fathers tend to have attractive daughters and attractive mothers tend to have attractive sons.
Heritability of facial attractiveness and masculinity-femininity
Estimating the Sex-Specific Effects of Genes on Facial Attractiveness and Sexual Dimorphism (pdf)
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4 comments:
I'm sort of cousins with a family of four siblings: the brothers are ruggedly handsome guys, but the sisters are too rugged to be terribly pretty. Is that pattern common among siblings?
As a hypothetical case: which movie star would you bet has a conventionally better looking sister: rugged Russell Crowe or delicate Johnny Depp?
Have there been any studies of this?
Steve,
Yes, the researchers behind the paper above have also found "facially masculine men tend to have facially masculine, less-attractive sisters." (Genetic Factors That Increase Male Facial Masculinity Decrease Facial Attractiveness of Female Relatives)
There's also this: Evidence of intralocus sexual conflict: physically and hormonally masculine individuals have more attractive brothers relative to sisters
And I think I've seen at least one other paper reporting similar results.
But according to the paper linked in the original post, there are also other genetic factors that influence the attractiveness of opposite sex relatives in the same direction (probably related to genetic load):
On the other hand, the positive genetic correlation
between male and female attractiveness and the negative
genetic correlation between male facial attractiveness and
female facial masculinity–femininity suggest that alleles
influencing variation in these traits are consistently bene-
ficial—or maladaptive—regardless of sex. One mechanism
for maintaining genetic variation in the face of such
directional selection is mutation-selection balance:
although some of the alleles affecting these traits are
conducive to both sexes’ reproductive success, a constant
influx of deleterious mutations is introduced each genera-
tion that maintains a degree of maladaptive variation in the
population (Houle 1992).
As a hypothetical case: which movie star would you bet has a conventionally better looking sister: rugged Russell Crowe or delicate Johnny Depp?
For a real case, see Bruce Willis's daughter Rumer Willis. She inherited his chin and jaw:
https://en.wikipedia.org/wiki/File:Rumer_Willis.jpg
article related to this topic:
http://www.femininebeauty.info/sexually-antagonistic-selection
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