Although most people believe sexual development begins with adolescence and ends sometime around late adulthood, it actually is a lifetime journey that we all participate in whether we realize it or not.

Throughout the life cycle, humans are in a constant state of sexual development – from cradle to just before the grave – with every phase offering new twists and turns in the journey.

Prenatal and Infant Development
Sexual development begins well before the infant is born. At the time of birth for infant girls, the ovaries have already begun to develop and will continue to develop slowly in size and weight until puberty, when they will further develop dramatically.

Estrogen secretion for baby girls is slight and constant. The fallopian tubes have a coiled appearance and the uterus of an infant girl is very small.

For boys, the structure of the testes is formed by the middle of the gestation period (or about five months into the mother’s pregnancy). Testosterone levels remain fairly similar as in female infants from the third month until the onset of puberty.

Adrenal androgen levels – the hormone that controls the development and maintenance of masculine characteristics – rise a few years before the onset of puberty and may influence skeletal development.

Infant Development and Healthy Curiosity
From birth, male babies are capable of erections and female babies are capable of vaginal lubrication. Signs of infant eroticism (erections and lubrication) are reflexes during the first year of life so that any touching or brushing of the genital area will likely trigger these “sexual” reflexes.

During infancy, genital fondling is not considered goal-directed behavior as it is with adult masturbation. For infants, rubbing the penis or vulva is a pleasurable activity like sucking thumbs or playing with toes. When parents overreact to this behavior, it can negatively impact how children learn to view themselves, their bodies and how they interact with others.

Toddler Development and Gender Identification
As children age, they quickly begin to recognize gender differences and begin to develop their gender identity (the feeling of conviction that they are male or female).

For example, a 2-year old boy is able to describe himself as a boy. From there he begins to learn the behaviors expected of him in his culture – his gender role. As he learns and accepts those roles and behaviors, he develops gender role identification.

Potty Training and Sexuality
At the same time children begin to gain an understanding of gender roles, they also begin to demonstrate the muscle control required for toilet training. Parents use a variety of techniques to facilitate toilet training, but underlying many of them in our culture is an emphasis on the dirtiness of excrement. After children have learned to eliminate bodily waste in the appropriate places, they often retain the idea that their genital area is dirty and bad, something that should not be touched to avoid spreading germs or waste. This is paralleled in our labeling of sexual stories or jokes as “dirty.”

Body Respect
The connection between genitals and dirt or being dirty can be especially true for girls. Generally, boys are taught to wipe themselves with toilet paper after they defecate but not when they urinate. Girls are taught to wipe themselves every time they use the toilet.

Because differentiating the urethra from the clitoris and the anus from the vagina is more difficult for a girl than it is for a boy to differentiate the penis from the anus, girls are likely to assume that the urethra, clitoris, vagina and anus are all dirty and should be avoided.

This is further compounded when girls reach puberty and are taught that menstrual bleeding is unclean, further reinforcing the association that the genitals are dirty. This strong association between sexual organs and dirtiness can have a significant negative impact on sexual functioning and experiences as an adult.

Preschool Development and Healthy Sexual Exploration
By preschool, children often have developed a strong curiosity about sexuality, which marks an important time in their sexual development.

Discouraging or punishing a child’s sexual exploration at this time can create guilty feelings about sex. Parents should acknowledge sexual curiosity without being overly-chastising to help foster a sense of competence and confidence.

During the preschool years, children express their sexuality in more social ways. Little boys and girls will kiss, hug and hold hands as they imitate adult behavior. Generally this fascination with sexuality is expressed through play, such as “playing house” or “playing doctor.”

Also around this time, children have developed the capacity for self stimulation, with most boys and girls able to achieve orgasm by the age of 5.

For many children this is also the time of the “primal scene,” when a child observes their parents having intercourse. The primal scene was at one time thought to have traumatic impact on the child’s psychosexual development. However, there is no evidence to support this theory.

How Family Response Impacts Individual Sexuality
The impact of observing parents in coitus is dependent on the general family environment. If parents are extremely private about showing affection, unrealistically avoid nudity and punish the child for their own interest in and exploration of their bodies, the child is likely to be overwhelmed by seeing his parents having intercourse. If children are angrily sent out of the room and never receive an explanation about what they saw, they are likely to develop an understanding of sex as something to be feared and avoided.

On the other hand, if a child is accustomed to an environment with affection and acceptance of their bodies, then the impact of the primal scene is likely to be minimal.

Late Childhood Development
During late childhood, children seem to naturally segregate themselves by gender. This period is called homosociality and generally begins by age 8 and peaks between the ages of 10 and 13.

This is the time when boys and girls have “cooties.” As children tend to play almost exclusively with members of their own gender during this period, homosexual behavior is more likely at this time than in later adolescence. This is a normal part of a child’s sexual development and seldom determines a person’s sexual orientation later in life.

While it is obvious that children experience sexuality from the moment of their birth, during late childhood and early adolescence, children also are exposed to sexual education in other ways, such as through school programs.

Generally, school programs follow one of two models. Abstinence-Only programs teach avoidance of all sexual behavior. Postponement and Protection programs promote a more thorough understanding of sex and contraception.

Research on the effectiveness of Abstinence-Only sex education programs, as practiced in Florida, suggests that they are ineffective in delaying sexual behavior in teens. Studies on Postponement and Prevention programs, however, have demonstrated their ability to delay sexual initiation, increase contraceptive use and decrease pregnancy rates among adolescents. These programs are generally most effective when targeted at younger people, before they have begun to experiment with sexual activity.

Early Adulthood Development
As adolescents age and grow, they transition into early adulthood, which lasts from around age twenty to age forty. Adult sexuality is shaped and groomed by early life experiences.

With each decade that passes, the definitions and dominant activities of this age range evolve. In general, individuals are getting married later in life and extending their stay in bachelorhood after adolescence.

Sexually, this can be a time of great pleasure or great conflict depending on the attitudes the adult has carried from childhood. Often, there is still a concern as to whether the individual is sexually “normal,” compounded by a heavy concern for physical appearance, sexual endowment and ability. Despite these common concerns, sexual activity is much higher among today’s early adults than in the past.

As times change, so do the sexual standards for men and women. One reason early adults are more sexually active now is due to a change in the double standard previously held towards men and women regarding premarital sex.

In addition to the changing standards, there also has been an increase in cohabitation before marriage. Currently, there are more than 3 million unmarried couples living together.

Unfortunately, an increase in sexual activity does not guarantee sexual satisfaction and happiness. Studies of college students have found high levels of sexual concern as well as high rates of sexual dysfunction. Even with these high rates of sexual occurrence, most young adults do not realize how common sexual concern and dysfunction is among their own peer group.

Individual Sexuality
With adulthood comes the ability to label and identify elements of individual sexuality. Adults have an understanding of what is sexually arousing to them as well as when they are aroused.

Sexual arousal is scientifically defined as “a state of activation of a complex system of reflexes involving sexual organs and the nervous system.” What does this mean?

Stages of Sexual Response
There are actually four stages to the sexual response cycle with each differing for men and women.

PHASE 1 is the Excitement Phase, which for both men and women results from physical or emotional sexual stimulation. For women the first sign of excitement is the appearance of vaginal lubrication. For men, an erect penis signals excitement.

Physical and mental distractions can disturb and negatively impact this stage. The degree to which each of these outcomes occurs varies from person to person.

PHASE 2 is called the Plateau Phase. It is during this phase that the outer third of the vagina begins to swell and narrows. This is a response that is especially important for men to understand: Penis size does not matter because whatever the size, the vagina will contract around it.

During the Plateau Phase, the female uterus engages in what is known as tenting where it becomes elevated. For males in this phase, the head of the penis begins to swell and the testes increase in size and rotate forward.

PHASE 3 of the sexual excitement phase is the orgasm. Up until the mid-twentieth century, women were thought incapable of achieving orgasm. With correct stimulation, this is where the building sexual tension is released and orgasm is achieved.

However, no two orgasms are ever the same. An orgasm is a total body response where even brain-wave patterns show distinct changes. Contrary to popular belief, most women do not ejaculate during orgasm.

PHASE 4 is called the Resolution Phase and this is where men and women are the most different, sexually speaking.

Females are capable of having multiple orgasms within a short time without regressing below the plateau phase. Males in this phase go through what is known as a refractory period, an amount of time where further ejaculation or orgasm is physically impossible. This amount of time varies with age as well as among individuals.

Middle Adulthood Development
From early adulthood, the individual transitions into middle adulthood, where changing physique and loss of youth are common concerns. Many older adults have a sense that time is running out and this is the time in life when midlife crises begin to take shape.

During this time, men are the most vulnerable to a midlife crisis, especially from a sexual perspective. They begin to evaluate their sexual ability and performance while comparing it to that of their youth. Sexual difficulty due to performance anxiety may be an issue at this life stage.

Some men will look toward younger sexual partners to ignite their sexuality. There is also a tendency to blame their sexual difficulties on others, such as life partners or spouses.

For women this is a very different time as they are less apt to be concerned with their sexuality and sexual performance. At midlife, women tend to be in a state of re-evaluating their roles in life, especially if they postponed a career to care for children who are no longer sharing the home.

The departure of the children can serve as a source of great stress where the woman realizes there is not much substance or quality in the relationships with her husband and friends. Or, it can be the start of a sexual reawakening, where the woman is free to revisit sexuality with her husband or partner.

Not everyone experiences midlife crises, though. For some this is a time of independence and sexual freedom. Women during this time have been found to be more assertive sexually, seeking to have their needs met instead of sexually participating to please their husbands.

By their late fifties, most men show a more sensitive emotional concern for their partners and those around them and display fewer behaviors of power and proficiency. For women this is about the same time when they begin to experience menopause. During this time, menstruation stops and women generally are no longer able to conceive children.

With the onset of menopause, lower levels of estrogen are present in the body. This loss of estrogen predisposes the vagina to shrink, experience a loss of elasticity and decrease production of vaginal lubrication following arousal.

Without thoughtful precautions, such as use of lubricant, intercourse can range from slightly uncomfortable to incredibly painful. Some studies have suggested that menopausal women may also experience a decrease in sexual desire in addition to the loss of orgasmic ability in the early stages of menopause.

Some women, however, have been found to have an increase in sexual desire as well as the ability to have an orgasm. This topic is still under great debate in the scientific community.

Late Adulthood Development
From this stage, individuals transition into late adulthood. In America, many people believe that sex is for the attractive, young and healthy and not for the elderly.

However, our needs for intimacy and sexual closeness do not vanish at age sixty. There are no biological mechanisms that shut down sexual functioning once an individual reaches a certain age.

One aspect that may impact sexuality at this time is poor health. If an individual is healthy they are more likely to have a normal interest and ability for sex. Research shows that there are many individuals over the age of 60 that engage in active, healthy sexual activity.

Men in this age group may begin to experience some physiological changes, though. Most men will find an increase in the amount of time it takes to become aroused and achieve a fully-erect penis. Once this does happen, they tend to be less firm than in previous years. The time following ejaculation until the male is able to ejaculate again, the refractory period, usually increases. The potential for experiencing performance anxiety at this stage is significantly greater if these biological changes are misinterpreted.

At this phase, many women lose elasticity and muscle tension in the vagina as well as orgasm intensity. But, clitoral function is generally not affected. Women will naturally experience the loss of elasticity described earlier in their vagina. However, women who engage in regular sexual intercourse experience less of this vaginal shrinking and have higher levels of the hormones that begin to decrease following menopause.

Despite these difficulties, individuals in late adulthood are frequently sexually active. Even after losing a partner, many report actively seeking out new partners. It is interesting to note that the assumption of late adulthood mirrors that of adolescence where abstinence is often assumed.

Regardless of the stage, sexuality is a life-long journey with twists, turns and detours along the way. It is important to remember that sexual development and exploration are natural processes that most every individual on the planet ventures through.

Whether people shout it from the rooftops or choose to keep their activities more private, sexuality is a normal and healthy part of all of us.

Further Reading on Sexuality/Sexual Development:
For parents, children and teens:
Everything You Never Wanted Your Kids to Know About Sex (But Were Afraid They’d Ask): The Secrets to Surviving Your Child’s Sexual Development from Birth to the Teens by Justin Richardson and Mark Schuster, Three Rivers Press, ISBN #1400051282

For adults:
With Pleasure: Thoughts on the Nature of Human Sexuality by Paul R. Abramson and Steven D. Pinkerton, Oxford University Press,
ISBN #0195146093

For parents:
Why Do They Act That Way? A Survival Guide to the Adolescent Brain for You and Your Teen, Free Press, ISBN #0743260775

Sarah Marie Weinstein Arnett is a second year graduate student in the clinical psychology program at the Florida Institute of Technology in Melbourne. Ms. Arnett also serves on the board for the Florida Society of Clinical Hypnosis. She has special interest and training in couples and sex therapy, EMDR, and clinical hypnosis.

Timothy Fortney, M.S., is completing his final year of doctoral studies at Florida Institute of Technology in Melbourne and will begin his internship at a community mental health organization in Ft. Wayne, IN, in the fall. Mr. Fortney also holds a master’s degree in counseling psychology from the University of North Florida and has specialized training and interest in couples and sex therapy, sex offender treatment, EMDR, trauma resolution and clinical hypnotherapy.