From PhysOrg:
The essence of male beauty is down to the way males use their genes rather than what genes they have, according to a new study into the sexual attractiveness of turkeys. Geneticists have long puzzled over why individuals of the same sex show a greater or lesser degree of sexual attractiveness. In other words – why are some people better looking than others when they're genetically similar?
In a new study, published today in the journal PLoS Genetics, scientists turned to male wild turkeys to solve the problem. They found that among turkeys that are brothers (and therefore share the majority of their genes), 'dominant' males show higher expression of genes predominantly found in males, and a lower expression of genes predominantly found in females, than their subordinate brothers. Therefore, dominant males were both masculinised and defeminised in terms of their gene express ion. A male's attractiveness is a function of how they express their genes, rather than the genes themselves.
More here.