Et’s first take a look at physical and psychosexual changes from birth to age 2. We would not label behavior as “sexual” during this time; however, there are many behaviors that arise out of curiosity

Physical Development: Fully Equipped at Birth

Our sexual anatomy becomes functional even before we are born; ultrasound has shown male fetuses with erections in the uterus, and some babies develop erections shortly after birth—even before the umbilical cord is cut (Masters et al., 1982). Female babies are ca­pable of vaginal lubrication from birth (Martinson, 1981). Infant girls produce some es­trogen from the adrenal glands before puberty, whereas infant boys have small testes that produce very small amounts of testosterone. Young children are even capable of orgasm!

Kinsey and his colleagues (1948, 1953) established that one-half of boys between the ages of 3 and 4 could achieve the urogenital muscle spasms of orgasm (though no fluid is ejaculated), and almost all boys could do it 3 to 5 years before puberty. Kinsey did not collect systematic data on the abilities of young girls to reach orgasm, though he did include some anecdotal stories on the subject. Still, there is no reason to think that girls should be any less able than boys to orgasm.

Psychosexual Development: Bonding and Gender Identification

The single most important aspect of infant development is the child’s relationship to his or her parents or caregivers. The infant is a helpless creature, incapable of obtaining nourishment or warmth or relieving pain or distress. The bond between the mother and child is more than psychological; a baby’s crying actually helps stimulate the secretion of the hormone oxytocin in the mother, which releases her milk for breast-feeding (Rossi, 1978; we’ll discuss this more in Chapter 12).

Pheromones are also important. Remember that in Chapter 7, we discussed how pheromones promote the bond between a mother and her infant (Kohl & Francoeur,

2002). Equally as important as the infant’s need for nourishment is the need for holding, cuddling, and close contact with caregivers. An infant’s need for warmth and contact was demonstrated in Harlow’s (1959) famous experiment, in which rhesus monkeys were separated at birth from their mothers. When offered two surrogate mothers, one a wire figure of a monkey equipped with milk bottles and one a terrycloth-covered figure, the monkeys clung to the terrycloth figure for warmth and security and ventured over to the wire figure only when desperate for nourishment. The need for a sense of warmth and se­curity in infancy overwhelms even the desire to eat.

As we discussed in Chapter 3, infants between 1 and 2 years of age begin to develop their gender identity (Lewis, 1987). After about the age of 2, it becomes increasingly dif­ficult to change the child’s gender identity (which is occasionally done when, for exam­ple, a female with an enlarged clitoris is mistakenly identified at birth as a boy). It takes a little longer to achieve gender constancy, whereby young children come to understand that they will not become a member of the other sex sometime in the future. By this age there is usually strong identification with one gender, which becomes a fundamental part of a child’s self-concept. Along with this identification begins knowledge of gender role behavior, the behaviors that society teaches are appropriate for a person of that gender.

Though gender role behavior undoubtedly has some biological component, it is primarily a product of modeling and direct teaching by the parents and other caretakers (Finan, 1997).