Cultural factors plays a minor role compared to biological factors. We are literally programmed to be attracted to health; therefore normal individuals who are not perverted in some way, will not be attracted to severely underweight or overweight people. Smooth skin with a clear complexion is universally seen as attractive. Bright, clear eyes is universally attractive. Athletic bodies are universally seen as attractive. Symmetrical features are universally attractive. White, even teeth are universally more attractive than yellow, damaged teeth. You get the picture.
There is not a woman in this world who thinks that Steve Buscemi is more attractive than Brad Pitt, and I doubt that any man thinks that Sandra Bernhard is more attractive than Angelina Jolie.
We are designed to appreciate beauty because it points to perfection; wherever there is beauty there is health, and a beautiful work of architecture is very likely to be solid - the most beautiful formula in math is always correct etc. Beauty is not just meaningless vanity, it is just symbolic of something far greater than the mere surface of it.
