What biological factors affect sexual attraction?

Depends on what kind of organism you are asking about. It often depends on the ratio of females to males. It might depend on the availability of mates. Some female birds use color or plumage as a guide (think peacocks). Some female birds find a nice nest to be sexy. read more

Attraction is more than looks: it combines smell, hearing (voice) and the visual clues. Some are at the subconscious level, driving us towards a person without being able to explain it clearly. Biology dominates us. read more

Sexual attraction is attraction on the basis of sexual desire or the quality of arousing such interest. Sexual attractiveness or sex appeal is an individual's ability to attract the sexual or erotic interests of other people, and is a factor in sexual selection or mate choice. read more