Physical attractiveness is the degree to which a person's physical features are considered aesthetically pleasing or beautiful. The term often implies sexual attractiveness or desirability, but can also be distinct from either. There are many factors which influence one person's attraction to another, with physical aspects being one of them. Physical attraction itself includes universal perceptions common to all human cultures such as facial symmetry ,  sociocultural dependent attributes and personal preferences unique to a particular individual.
Sexual attraction , in species which reproduce sexually , is attraction to other members of the same species for sexual or erotic activity. This type of attraction is often important for the survival of sexually reproducing species, while in many species serves no immediate reproductive goal. Sexual attractiveness in non-human animals depends on a wide variety of factors. Often, there is some element of the animal's body which exists for sexual attraction, like the bright plumage and crests of some species of birds. In many species, there are behaviours which appear to be sexual display.
Genetic sexual attraction is a concept in which a strong sexual attraction may develop between close blood relatives who first meet as adults. There is no direct evidence for genetic sexual attraction being an actual phenomenon,  and the hypothesis is regarded as pseudoscience. The term was coined in the US in the late s by Barbara Gonyo, the founder of Truth Seekers in Adoption, a Chicago-based support group for adoptees and their new-found relatives. Because many traits are at least partially determined by genetics, genetic sexual attraction is presumed, according to those who believe in the concept, to occur as a consequence of genetic relatives meeting as adults, typically as a consequence of adoption. However, this is a very rare consequence of adoptive reunions.
A demisexual person is someone who does not experience sexual attraction to another person unless or until they have formed an emotional connection with that person. The term demisexual comes from the orientation being "halfway between" sexual and asexual. Nevertheless, this term does not mean that demisexuals have an incomplete or half-sexuality, nor does it mean that sexual attraction without emotional connection is required for a complete sexuality.