Human sexuality is the way people experience and express themselves sexually. This involves biological, erotic, physical, emotional, social, or spiritual feelings and behaviors. Because it is a broad term, which has varied over time, it lacks a precise definition. The biological and physical aspects of sexuality largely concern the human reproductive functions, including the human sexual response cycle. Someone's sexual orientation is their pattern of sexual interest in the opposite and/or same sex. Physical and emotional aspects of sexuality include bonds between individuals that are expressed through profound feelings or physical manifestations of love, trust, and care. Social aspects deal with the effects of human society on one's sexuality, while spirituality concerns an individual's spiritual connection with others. Sexuality also affects and is affected by cultural, political, legal, philosophical, moral, ethical, and religious aspects of life.Interest in sexual activity typically increases when an individual reaches puberty. Although no single theory on the cause of sexual orientation has yet gained widespread support, there is considerably more evidence supporting nonsocial causes of sexual orientation than social ones, especially for males. Hypothesized social causes are supported by only weak evidence, distorted by numerous confounding factors. This is further supported by cross-cultural evidence, because cultures that are very tolerant of homosexuality do not have significantly higher rates of it.Evolutionary perspectives on human coupling, reproduction and reproduction strategies, and social learning theory provide further views of sexuality. Sociocultural aspects of sexuality include historical developments and religious beliefs. Some cultures have been described as sexually repressive. The study of sexuality also includes human identity within social groups, sexually transmitted infections (STIs/STDs), and birth control methods.