The Viennese analyst Sigmund Freud revolutionised the concept of child development with his theory, developed in the early 20th century, that adult sexuality stems from childhood experience. He believed that human beings go through five stages of psychosexual development based on a particular erogenous zone and that children who don't successfully negotiate a particular stage can experience sexual or emotional problems in adulthood.
Freud believed that psychosexual development begins with the oral phase, from birth to 18 months old, when the child learns to perceive his mother's breast as a source of comfort and nourishment. According to Freud, the infant can become orally fixated in adulthood if he feels deprived or experiences distress during this stage of development. Smoking, drinking too much alcohol and excessive eating have been linked to oral fixation in adults.
The anal phase is marked by the beginning of toilet training when the child is aged between 18 months and 3 years old. She must learn to control his bowel movements, along with other aggressive desires. At this stage, the child derives pleasure from eliminating and retaining faeces and begins to realise the power this gives her over her parents. Freud believed that anal fixation results from parents being too strict with children during toilet training. The anally fixated adult may be obsessively clean and orderly and enjoy exerting control over others. On the other hand, children whose parents are too lenient during this phase of development may be grow up to become messy and disorganised adults.
The term "penis envy" derives from Freud's theories about the phallic stage of development. He believed that children become attracted to their parent of the opposite sex when they are between four and five years of age. They also become hostile and envious towards the same sex parent. In boys, this is characterised by the "Oedipus Complex," which derives from the Greek myth about a young man who inadvertently killed his father and married his mother. In girls, it is known as the "Electra Complex," although this term was coined by Freudian analysts and Freud himself didn't believe a girl developed an unconscious sexual attraction toward her father, according to AllPsych Online. Freud believed that boys who cannot successfully resolve this conflict may experience sexual anxiety and guilt in adulthood.
Children go through the latency stage from the age of six until the onset of puberty. Sexual urges remain repressed as children become more independent of their parents and learn, through developing peer relationships, to interact with other people and respond to their needs.
Sexual urges are reawakened at the onset of puberty and the young adult who has successfully negotiated the previous stages of development directs his attention towards peers of the opposite sex. Pleasure is primarily focused on the genitals as young people fulfil a desire to procreate and enjoy mutually rewarding relationships.