Incest itself is largely taboo, and is a crime in many countries. Originating in Japan in the 1980s, the genre subsequently spread to North America and Europe, and crossed over into gay pornography. Target audience are teenage / young adult women. Pornography is often distinguished from erotica, which consists of the portrayal of sexuality with high-art aspirations, focusing also on feelings and emotions, while pornography involves the depiction of acts in a sensational manner, with the entire focus on the physical act, so as to arouse quick intense reactions. It is used, for example, at fertility clinics to stimulate sperm donors. Some straight actors have started acting in gay porn only to be accused of being gay while others first step was to strictly do solo scenes. The concept of lesbian, to differentiate women with a shared sexual orientation, is a 20th-century construct. Typically featured are hentai porn hitting, choking, name-calling and hair-pulling. Ass to mouth pornography shows the transfer of a performer penis from a second performer anus gay boy porn to that same second performer mouth in a single shot. Women who perform in lesbian pornography often do not consider themselves lesbian or bisexual. Pornography may fall into more than one genre. Mammary intercourse is a sex act, performed as foreplay or as non-penetrative sex, that involves the stimulation of the male penis by the female breasts and vice versa. Often, strong views are expressed with regard to anal sex; it is controversial in various cultures, especially with regard to religion, commonly due to prohibitions against anal sex among gay men or teachings about the procreative purpose of sexual activity. The object or situation of interest is called the fetish; the person who has a fetish for that object/situation is a fetishist. Dwarfs or midget pornography features performers who are dwarfs/midgets. This mature milfs can, however, redirect semen into the bladder . The term Asiaphile is sometimes used to describe the same phenomenon as is yellow fever .