I have seen references to "sexual selection" and "Fischerian runaway sexual selection " in this thread. Related?
Not just related, "sexual selection"
is the name we give the selection pressures for attractiveness, aesthetics, admiration and anything else that contributes to general hornyness.
I wanted to make three points in my message:
1. Other than determining what sex you are, the X-Y chromosome thing is a relatively minor bit and has practically no value in determining attractiveness.
2. The entire genome of a person working in concert to produce the complete outward phenotype is the key to sexual selection.
3. The genotype is randomly determined.
Sexual selection pressures certainly can cull/enhance specific traits (or rather combinations of traits ie. combinations of genes) creating a "bias" for/against those traits in a population, but in the end the entire genome as a single package is what is being selected.
So what is happening is that the genotype of an individual is randomly determined but this randomness is limited to the traits available in the population and is "biased" by the prevalence of that trait in the population. The more people with blue eyes in the population the more chance for blue-eyed babies. But no baby is guaranteed the blue-eye trait.
The chance combination of all the traits that go into making what we would consider a beautiful Miss World may not, probably will not, occur in her sisters as well.