Thus, similar immune systems may be more vulnerable to infectious diseases see Major histocompatibility complex and sexual selection. A woman's clitoris may withdraw slightly and there is more lubrication, outer swelling and muscles tighten and reduction of diameter. Some Hindu communities in India prohibit cousin marriages. Wilson said it takes an outside party to put an end to the father's incestuous behavior, no matter how much a father pleads he will stop. Incestuous relationships are considered so severe among chillulim HaShem , acts which bring shame to the name of God, as to be, along with the other forbidden relationships that are mentioned in Leviticus 18, punishable by death as specified in Leviticus National sex surveys given in Finland in the s revealed aging men had a higher incidence of sexual intercourse compared to aging women and that women were more likely to report a lack of sexual desire compared to men. Sexual activity can be consensual, which means that both or all participants agree to take part and are of the age that they can consent, or it may take place under force or duress, which is often called sexual assault or rape. Some may become hospitalized, alcoholic, psychotic or depressed. Typically, a woman's vagina becomes lubricated and her clitoris becomes swollen. Hmong culture prohibits the marriage of anyone with the same last name — to do so would result in being shunned by the entire community, and they are usually stripped of their last name[ citation needed ]. Sexual experiences help teenagers understand pleasure and satisfaction. When this need was satisfied, they felt better about themselves. The mother in incest families often is a homemaker who is financially dependent on the husband, Wilson said. However, because close relatives share a large fraction of their alleles , the probability that any such rare deleterious allele present in the common ancestor will be inherited from both related parents is increased dramatically with respect to non-inbred couples. Types[ edit ] Gerda Wegener 's artwork "Les delassements d'Eros" "The recreations of Eros" , which depicts sexual activity by two women Sexual activity can be classified in a number of ways: The self-determination theory can be applied to a sexual relationship when the participants have positive feelings associated with the relationship.