Sexual Development

Sexual development, also called puberty, is a normal stage of life during which adolescents experience many physical, cognitive, and emotional changes.

Not a Day at the Beach

"Mostly I'm pretty scared because I don't know if I'm normal or, you know, just strange. My body seems to be changing but not like some of my friends. I still look pretty much like a little kid and my best friend looks like he's 18 or something. I don't want to go near the gym anymore because then I'll have to take a shower. I know the other guys are going to laugh at me because I, well, you know, just don't look developed."—John, age 13.

"Now I have zits all over my face, my nose is too big and my breasts are too small. It really bothers me. I don't think guys will ever notice me, let alone like me if my body stays like this—I'm a disaster."—Dominique, age 14.

"No one had told me anything about menstruation. When I started to bleed and nobody was at home, I got so scared I called 911."—Aisha, age 12.

During adolescence the body a child has had for several years seems to become different and sometimes strange. This phase of development is referred to as puberty and involves rapid changes in the body, including sexual maturation. Bodies change, attitudes about self and others change, thinking abilities change, and interest in sexual activities changes as well. The good news is that puberty does not last forever—most people get through it by age 18.

Changing Bodies

Adolescence in Western societies spans the age range from about 8 to 20. During this period there are major physical and emotional changes associated with sexual development. This time is called puberty.

* hormones are bodily substances that originate in a gland or organ. The hormones most commonly referred to in regard to sex are androgens and estrogens.

Puberty is the growth stage in which the reproductive organs mature. Girls begin puberty, on average, about two years before boys. For girls, the body changes associated with puberty usually begin between the ages of 8 and 13. For boys, the normal age range for the start of puberty is between 10 and 14. What starts puberty is unknown, but the hypothalamus, a small area located deep within the brain, plays a key role. During puberty the hypothalamus and pituitary gland, a pea-sized organ located just beneath the hypothalamus, send out chemical messages that cause the gonads, or sex glands (testes in boys, ovaries in girls), to increase production of sex hormones * (testosterone in boys and estrogen in girls). With the increase in these hormones, the body begins to develop secondary sex characteristics (body hair, breasts, deeper voice, etc.) as well as to undergo a growth spurt.

Anthropologist Margaret Mead studied the sexual development of adolescents across cultures, discovering that different cultures have different rites of passage to mark the milestones in an individual's sexual development. Her landmark book Coming of Age in Samoa: A Psychological Study of Primitive Youth for Western Civilization was published in 1928 and still is a best seller. AP/Associated Press
Anthropologist Margaret Mead studied the sexual development of adolescents across cultures, discovering that different cultures have different rites of passage to mark the milestones in an individual's sexual development. Her landmark book Coming of Age in Samoa: A Psychological Study of Primitive Youth for Western Civilization was published in 1928 and still is a best seller.
AP/Associated Press

The organs involved in sexual reproduction also enlarge and develop. For girls this series of changes leads to menstruation and signals that the body is capable of sexual reproduction, or having babies. For boys these changes lead to the production of sperm. While boys may have experienced erections throughout childhood, ejaculation, the release of sperm in a fluid called semen, is only possible when this developmental level has been achieved.

Unfortunately, many studies continue to show that neither girls nor boys are prepared for the physical changes that make their bodies seem strange and foreign. Most girls report they knew little if anything about what usually is referred to as a "period" before their first experience. It also is typical for boys not to understand their newly acquired potential for ejaculation. Menstruation and ejaculation can be quite shocking and frightening experiences if one is unaware and unprepared.

Changing Attitudes, Changing Thoughts,
Changing Emotions

Puberty is a normal developmental stage that involves rapid and dramatic changes. In addition to physical changes, adolescents also experience changes in mood, thinking, and in social interests.


Changes in hormones in the adolescent body can trigger sudden and unpredictable changes in moods. One minute a boy or girl may be laughing and then, for no apparent reason, he or she can suddenly become angry or tearful. The different feelings that adolescents experience often make them feel like their emotions are on a roller coaster. The increased production of sex hormones is just one of many factors that contribute to these mood swings.


During this stage of life, adolescents develop the ability to think in more abstract and logical ways. They have a greater ability to examine their own, as well as other's, thoughts. These improved cognitive abilities often contribute to the disagreements between adults and adolescents as the adolescent is trying out new ways of thinking about issues and the world. If adults are not prepared for the changing nature of the adolescent's thought process, then the adolescent may feel as if he or she is being misunderstood or "treated like a child." Similarly, since adolescents are just beginning to develop these different cognitive abilities, there may be times when they want to think and act more like their younger selves. The adults around them need to respond to these changes and provide appropriate, challenging opportunities, but not opportunities that will overwhelm or frustrate the adolescent. The adults surrounding the adolescent are also learning about this changing, new person and are undergoing a "development" process, too!


Adolescents are also changing the way they think about themselves and others. Adolescents at this developmental stage are quite involved with their own thoughts and feelings. Many adolescents believe that everyone is as absorbed with himself or herself as he or she is. Additionally, adolescents at this time believe that others are looking at them or thinking about them in a critical manner. This may cause some adolescents to be very sensitive about body image, minor mistakes they make, or differences between themselves and others. Sometimes people refer to adolescents as "hyper-sensitive," which means that others feel that adolescents care too much about relatively minor things. For the adolescents, however, this hypersensitivity is part of the normal process of developing an understanding of who they are.

Alfred C. Kinsey and his colleagues interviewed men and women about their sexual behaviors and published two influential reports, Sexual Behavior in the Human Male (1948) and Sexual Behavior in the Human Female (1953). Archive Photos
Alfred C. Kinsey and his colleagues interviewed men and women about their sexual behaviors and published two influential reports, Sexual Behavior in the Human Male (1948) and Sexual Behavior in the Human Female (1953).
Archive Photos


Adolescents have a new sense of personal uniqueness or "egocentrism." At this stage, adolescents believe that no one else can ever understand how they feel, not parents or even friends. Sometimes, to maintain a sense of personal uniqueness, adolescents may have ideas and beliefs that seem inaccurate or unrealistic. This is a normal reaction to the changes that the adolescent is undergoing.


Sometimes adolescents feel they are indestructible or invulnerable to danger. This can lead to reckless behaviors such as drug use, fast driving, "daredevil" behaviors, suicidal thoughts, or sexual promiscuity. The adolescent may be unable to comprehend accurately the potential risks and negative outcomes of these reckless acts. This is another area of potential conflict between adolescents and adults: adults are responsible for keeping adolescents safe, and adolescents perceive adult actions to be overly controlling, overly cautious, or "out of touch."

What About Sex?

Adolescent development comes with many new and different physical and emotional feelings. Some of the most confusing may be the sexual thoughts that cause sensations or reactions in the body. Both girls and boys experience sexual feelings. These feelings are pleasurable and exciting and perfectly normal. Sometimes it is difficult to understand what one is expected to do with these new sexual feelings. Adolescents are aware that adults and the society in which they live have many, often conflicting, ideas about sex. For example, even though masturbation is a normal part of human sexuality, many people feel embarrassed to talk about it or may feel it is harmful or sinful. Adults are important resources who can help adolescents learn that sexual development and the physical changes of their bodies are normal. Unfortunately many adults are reluctant to discuss these issues, and adolescents are left with the impression that there is something wrong or shameful about the natural functioning of their bodies.


When girls reach a particular stage of development, usually between ages 9 and 15, menstruation (MEN-stru-A-shun) begins. Often referred to as a "period," the word "menstruation" comes from the Latin word "mensis" meaning month. Each month an egg (ovum) is released from a woman's ovaries. This is called ovulation. The egg carries half of the genetic information needed to create a baby. The other half is contained in the sperm cell provided by the male. If the egg is fertilized by sperm, the embryo implants in the uterus where it will grow. If the egg is not fertilized, the soft lining of the uterus is shed and passes out of the woman's body. Every month a woman's body readies for a possible pregnancy. The time between one menstruation and the next is about a month and is called the menstrual cycle.


Menstruation is a normal and important fact of a woman's life. Many young women are not adequately informed about menstruation. One study found that 43 percent of women felt frightened, panicky, or ill when they started to menstruate for the first time. About one-third of women in another survey did not know about menstruation before they began menstruating. It is important for girls to be told about the various physical and emotional changes surrounding menstruation. For example, it is common for a woman's breasts to feel swollen and tender before her period begins. Other women experience temporary weight gain of a few pounds or sudden cravings for carbohydrates such as chocolate prior to their periods. Some women feel they are absent-minded or disorganized or that their emotions are out of control before their periods begin. Many women experience cramps, pains in the lower abdominal area, at the start of their periods. All of these experiences are normal and it is important that young women are aware of these potential feelings as a natural part of menstruation.

Did You Know?

There are between 15,000 and 30,000 whiskers on a man's face.

Erections and Ejaculation

When boys reach puberty they may begin to experience more frequent erections. Erections occur when blood rushes into the penis, causing it to grow and stiffen. Ejaculations occur when sperm mixes with fluids from a gland called the prostate gland, and exits through the opening of the penis. It is through ejaculation that sperm leaves the male's body to enter the female's body when they combine during sexual intercourse to begin a pregnancy. Not all erections lead to ejaculations or sexual intercourse. As boys mature they may also have erections and orgasms during sleep or pleasurable dreams. These are often called "wet dreams" or nocturnal emissions. Nocturnal emissions are usual and normal for boys. If a boy's pajamas or sheets are wet and sticky upon awakening, he has probably had a wet dream. Sometimes a full bladder may cause an erection so it is not uncommon for males to awaken with an erection. Because there are many ways to excite the penis to erection, sometimes men have erections for no apparent reason, or even at inconvenient times. Boys may have erections at times that can be embarrassing, perplexing, or even anxiety provoking. While it may seem embarrassing and troublesome, it is all quite normal. Discussing these confusing moments with someone the young man trusts and is comfortable with can help to reassure him about these experiences.

William H. Masters and Virginia E. Johnson were a married couple who studied sexual desire, arousal, and orgasm. They published their findings in the books Human Sexual Response (1966) and Human Sexual Inadequacy (1970). AFP/Corbis
William H. Masters and Virginia E. Johnson were a married couple who studied sexual desire, arousal, and orgasm. They published their findings in the books Human Sexual Response (1966) and Human Sexual Inadequacy (1970).


Masturbation is the self-stimulation of the genitals to achieve pleasurable sensations, sometimes resulting in sexual orgasm. It is one of the most common human sexual expressions. Children from about the age of 21/2 may masturbate. A recent study has shown that one-third of females and two-thirds of males report masturbating before they reached adolescence. Many parents are hesitant to condone or express their approval of masturbation. Many religions feel that masturbation is improper. It is a difficult topic to discuss openly even though the majority of teenage boys and girls report having masturbated by the end of puberty.

While masturbation is a safe and available release for sexual tension, many people masturbate and many do not. It is a matter of personal choice, guided by one's beliefs and values.

Staying Safe

While most people engage in some form of mutual sexual interaction at some time in their lives, when, with whom, and why are big questions that should be carefully considered before activities begin. In addition to the emotional price of having sex before one is ready, it can also pose some potential health risks and other problems. Pregnancy and sexually transmitted diseases are two health issues that may arise from sexual intercourse.


Pregnancy is a natural outcome of sexual intercourse. Unless an adult couple is prepared and ready to start a family, an unexpected pregnancy can cause many problems. This is one of the reasons it is so important to consider the consequences of acting on one's sexual desires before engaging in intercourse. There are many ways to prevent pregnancy. These methods are called contraception or birth control. The most effective method of contraception, and the only one that is 100 percent effective, is to refrain from all sexual intercourse until ready for pregnancy. This is sometimes called "abstinence." Many religious groups and many parents support the idea that sexual intercourse should only occur within a marriage.


There are many methods of contraception. Using no "protection" against pregnancy by trying to time sexual contact or trying not to ejaculate during intercourse are generally not considered effective. There are other methods of contraception that allow a couple to engage in sexual intercourse with protection against unwanted pregnancy.

Men may use a condom, sometimes referred to as a rubber or jimmy, during intercourse. A condom is a soft, thin latex or polyurethane cover that fits over an erect penis.

Other forms of contraceptives include birth control pills, diaphragms, intrauterine devices or IUDs, cervical caps, Norplant, or Depo Provera. These methods are all prescribed forms of contraception that can only be obtained from a doctor or health clinic. These methods are only used by women and require a thorough physical examination before they are prescribed.

It is important to understand that any decision about contraception, like any decision about sex, should be an informed decision. Discussions with parents, health professionals, counselors, and trusted adults should be part of making mature and informed decisions about sexual activity. Many states regulate the age at which a person can receive prescription birth control methods. Often people who are younger than 18 years of age must have the permission or consent of parents or guardians to obtain these birth control measures.

Sexually transmitted diseases

Although the proper use of condoms can decrease the risk, abstaining from intercourse or other risky sexual activities is the only sure way to prevent the spread of HIV/AIDS, gonorrhea, chlamydia, syphilis, herpes, and other sexually transmitted diseases.

Sexual Orientation

Sexual orientation refers to one's feelings for and sexual attraction to other people. People can be heterosexual, homosexual, or bisexual. Most people's orientation is heterosexual (attraction to the opposite sex), but homosexual (attracted to the same sex) and bisexual (attracted to both sexes) orientations are normal as well. It is estimated that as many as 10 percent of people are homosexual and there are no reliable estimates for the prevalence of bisexuals. There are many problems with obtaining reliable estimates of the numbers of gays, lesbians, and bisexuals in the population because of the ongoing discrimination they face due to their sexual orientation.


During adolescence one's sexual orientation is often unsettled. Some people engage in various forms of sexual experimentation during early adolescence. This experimentation is generally due to opportunities that present, curiosity, or family or peer pressure. These may not always be consistent with a person's natural sexual orientation or attraction.

What this means is that some people might have some alternative sexual feelings or activities (for example, homosexual sex) during adolescence. These people may go on to be fully heterosexual. Similarly, individuals who identify themselves as homosexual may have heterosexual experiences during adolescence. For some people, adolescence is a time of curiosity and exploration. This is considered normal and generally has nothing to do with how someone will "grow up."

How does sexual orientation develop?

Sexual orientation is a natural fact of human life and central to everyone's core identity. This question is most often asked about same-sex and bisexual orientations. Do people choose to be homosexual or bisexual? Are they born that way? This has been a long-standing and controversial debate. Many scientists now believe that sexual orientation is not a matter of choice. These scientists think people are born with their sexual orientation, just like they are born with their eye or hair color. Other scientists believe that experiences during a person's childhood contribute to his or her sexual orientation. Up to this point, there is no conclusive scientific evidence that completely answers the question of what makes a person gay or straight.

See also
Body Image
Gender Identity



Bell, R. Changing Bodies, Changing Lives: A Book for Teens on Sex and Relationships. New York: Random House, 1988.

Harris, R. H. It's Perfectly Normal. Cambridge, MA: Candlewick Press, 1996.

Madaras, L., and A. Madaras. My Body, My Self for Girls. New York: Newmarket Press, 1993.

Madaras, L., and A. Madaras. My Body, My Self for Boys. New York: Newmarket Press, 1995.

Marcus, E. What If Someone I Know Is Gay? New York: Price Stern Sloan, 2000.

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