First, there is the so called LEK PARADOX, which states that females of the species choose a certain male based on specific characteristics (male lions with manes, peacock feathers, the size of white forehead patch of flycatcher male).This raised one big question: Are females obtaining genetic benefits for their offspring by choosing males with specific traits? Even so, there are researchers that suggest that sexual selection is the cause of greater genetic diversity and these characteristics are not always inherited.
Being physically attractive is sometimes associated with good health which would be passed onto future generations, giving them a higher chance of survival.
Genetics can impact both visible (skin, eye colour, hair colour, strenght, height) and invisible traits (that can sometimes manifest in visible ways), but in the end an individual’s attractiveness is subjective and these theories can be controversial.