I think, re human facial beauty, much of what we find attractive comes down to symmetry.
Take this famous guy ...

I'm not attracted to Muhammad Ali but he was pretty photogenic in his prime. I'm fairly sure lots of women found him attractive ... probably some gay guys, too, I guess. His face was symmetrical, his teeth were straight, white and well-formed. His skin was clear and without blemishes. He was tall-ish and well-proportioned - not too fat, not too thin, not too stocky and not too gangly. His shoulders were broad and his waist was fairly small.
Now take this guy ...

Joseph Merrick was unfortunately extremely deformed. I'm not sure what he suffered from - it could have been neurofibromatosis or proteus syndrome, or both. He may have been a beautiful person on the inside but he had literally zero physical beauty. Notice, too, his asymmetrical head, face, arms, body. What woman in her right mind would consider this guy attractive? She would have to be off her raving titties to want this guy's babies.
I feel kinda bad talking about him like this but I'm not ripping on him, just stating what I think is the obvious.
Although physical beauty is subjective to some degree, genetics does come into it. Women wouldn't want to have Joseph Merrick's babies because his appearance is due to his genetics (genotype gives phenotype). There must have been something about Merrick's DNA for him to have grown up and looked like he did. Babies inherit some of the father's DNA. And women wouldn't want a chance of their babies to look like him.
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I read somewhere that there is a link or correlation between high fertility levels and young women who have an hour-glass shape. <---- is this correct?
If so, this kinda makes sense because the hour-glass shape is very attractive for adult males.