11.3 Sexuality in Early Adulthood

Sexual Maturity and Sexual Behavior

The Sexuality Education Resource Centre (SERC) in Manitoba, Canada, which states that a person’s sexuality is self-defined and can change over time depending on age and circumstances. The SERC portrays sexuality as being in a “wheel” composed of different components that interact with each other (SERC MB, n.d.), as seen in Figure 11.13. Here, we’ll likewise define sexuality as a person’s feelings, beliefs, and behaviors regarding attraction to others, sexual activity, and gender identity.

Figure 11.13 Sexuality involves several different components, each of which may change over time. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Sexuality is a complicated concept with many influences, including biology, culture, religion, the views of our family and friends, and the portrayals of sexuality in mass media (Macleod & McCabe, 2020; Potard et al., 2008) (Figure 11.14). Because culture evolves, so do attitudes and behaviors regarding sexuality. For several decades, the General Social Survey (GSS) from the University of Chicago has tracked U.S. societal opinions on attitudes toward various facets of sexuality. Over that time studies have found greater acceptance toward living together before marriage and having sex before marriage (GSS Data Explorer, 2022; Harding & Jencks, 2003). However, in the United States and some European countries, these behaviors are now widely accepted, though they are still frowned upon or even prohibited in other countries (Rokach & Patel, 2021). Societal acceptance of non-heterosexual relationships, and the experiences people have when coming out, likewise vary by cohort (Martos et al., 2015; van Bergen et al., 2021). In some parts of the world, young females undergo procedures meant to decrease sexual pleasure, and marriage sometimes occurs before reaching puberty to reduce the incidence of premarital sex (Rokach & Patel, 2021; UN Women, 2019). However, in other cultures, premarital sex is considered a natural aspect of the transition from adolescent to adult and is encouraged (Christensen, 1960; Rokach & Patel, 2021).

Figure 11.14 Attitudes toward sexuality and sexual behavior can be affected by one’s culture. (credit: “Close-up of a couple smiling and holding hands” by Chona Kasinger/Disabled and Here, CC BY 4.0)

Why do people engage in sexual activity? Beyond the obvious reasons that it’s enjoyable, there are psychosocial reasons as well. Sexual activity is a way to express feelings to and establish connections with others, an important developmental task of emerging adulthood. Sexual interactions can also be a method of exploring one’s identity, particularly for LGB youth who are questioning their sexual orientation or who feel the need to downplay their sexual orientation due to social disapproval (Phillips II et al., 2019). Social factors may also influence this (Figure 11.15). A study examining heterosexual women’s same-sex encounters—specifically, kissing publicly—at college parties indicated that there was no single motive for this behavior; instead, it was motivated by one of several factors, such as being drunk, wanting to experiment, and enjoying the attention this behavior produced, especially attention from men (Yost & McCarthy, 2012). Sexual activity is also considered to be a standard element of romantic relationships, and some people engage in it out of feelings of obligation or duty—feelings that can be exploited, particularly in cultures where women are expected to be submissive and marital rape isn’t regarded as a crime (UN Women, 2019).

Figure 11.15 The experience of sexuality is unique to everyone. (credit: modification of work “YuLein” by “Yuc j”/Wikimedia Commons, CC BY 3.0)

The experience and expression of sexuality are unique to everyone. The peak of sexual activity generally occurs between the ages of 18 and 24, though the number of adults in this age group who were sexually active decreased somewhat between the years 2000 and 2018, especially men (Ueda et al., 2020). Becoming sexually active is a common part of growing up, although it’s not a mandatory element (i.e., people who are asexual or who abstain from sexual activity for religious or other reasons aren’t somehow “defective”). Sexual activity is also, for many people, a healthy and enjoyable aspect of their lives. However, sometimes sexual activity has unwanted health consequences, such as sexually transmitted infections or unintended pregnancy.

Sexual Orientation and Gender Identity

Recent data indicate that in the United States, about 7 percent of the population identifies as LGBTQ+, including 20 percent of adults in “Generation Z”, the group born between 1997–2012 (Jones, 2024). Looking beyond the U.S., a survey of 30 countries indicated that about 9 percent of the world’s population identifies as LGBTQ+, although there’s a lot of variability between countries; for example, 15 percent of Brazil’s population identifies as LBGTQ+, but only 4 percent of Peru’s population does (Jackson, 2023). In both sets of data, the most common LGBTQ+ identity was as bisexual; about 4 percent of the U.S. and world population identify as bisexual, and 57 percent of the LGBTQ+ adults in the U.S. claim this identity (Jackson, 2023; Jones, 2024).

Figuring out one’s sexual orientation and gender identity doesn’t look the same for everyone. In cultures where LGBTQ+ people are stigmatized or even criminalized, there may be significant risks to coming out, and some people may choose not to do so until later in life if at all (Rosati et al., 2020). Even in countries with LGBTQ+ friendly policies, that doesn’t mean that individual people or communities will be accepting. Also, “coming out” isn’t a singular event, but often involves several tasks, often described as identifying an attraction to others, identifying as having a particular sexual orientation, having one’s first relationship corresponding to that sexual orientation, and disclosing sexual orientation to others (Hall et al., 2021; Martos et al., 2015). These tasks typically don’t occur simultaneously, although they do appear to happen in a fairly consistent order, and the specific timing of these tasks may vary. In general, men achieve these tasks earlier than women, and people identifying as gay or lesbian achieve most of these tasks earlier than people identifying as bisexual. There are also cohort differences in that people ages 45–59 reported the relationship and disclosure tasks occurring later than people ages 30–44, who in turn reported these tasks occurring later than people ages 18–29. These differences likely reflect changing societal attitudes regarding the acceptability of non-heterosexual relationships (Martos et al., 2015; van Bergen et al., 2021).

The study by Martos and colleagues indicates that identifying as lesbian, gay, or bisexual commonly happens in mid-adolescence, but disclosure to others may not occur until emerging adulthood (2015). Emerging adulthood, as we’ve already seen, is a time of continued identity exploration and commitment after we’ve gained more independence. This pulling away from our family is often accompanied by increased connections with similar peers. Studies of college students in the United States suggest that between 7 percent and 14 percent of heterosexual women and roughly 4 percent of men report having at least one same-sex encounter. These rates are lower in other countries, such as Thailand, most likely due to cultural differences in the acceptability of same-sex involvement (Morgan, 2013). Heterosexual women consistently report more same-sex attraction and encounters than heterosexual men do, potentially because of internalized standards of “appropriate” male behavior and a general greater incidence of sexual fluidity in women (Morgan, 2013; Yost & McCarthy, 2012) (Figure 11.16).

Figure 11.16 Sexual attraction and sexual experiences are determined by a complex combination of factors. (credit: modification of work “Nick and Andy celebrate their commitment in Minnesota” by Freedom to Marry/Flickr, CC BY 2.0)

Sexually Transmitted Infections

Because sexual activity generally peaks during this time, it’s not surprising that the years from ages 18–24 are also the peak years of risk for contracting a sexually transmitted infection (STI), a disease caused by certain types of viruses, bacteria, or microorganisms and spread through contact with bodily fluids such as semen and blood. According to the Centers for Disease Control and Prevention (CDC), in 2022 almost half the new cases of STIs occurred in people between 15 and 24 years of age (CDC, 2024). The use of the phrase “sexually transmitted” is a little misleading, because some STIs can be acquired outside of sexual activity; for example, HIV can be passed to nursing babies through breastmilk. However, regardless of the mode of transmission, the health effects of STIs are the same.

There are several different STIs, each with its own cause. Syphilis, chlamydia, and gonorrhea are caused by bacteria. Trichomoniasis is caused by a parasite. Common symptoms of these four STIs are painful urination, discharge (including blood) from the genitals or anus, and pelvic or abdominal pain, although some people may not have any symptoms. These STIs can be treated with antibiotics; however, a person can get re-infected if they come into contact with the bacteria/parasite again. It’s also important to take the antibiotics as directed, including taking all the medicine even if symptoms improve. Only taking some of an antibiotic prescription is believed to cause bacteria to become drug-resistant (Muteeb et al., 2023), making future infections harder to treat.

Other STIs are caused by viruses. Genital warts are caused by the human papillomavirus (HPV) and typically occur as small cauliflower-like bumps on the genitals, although some people may not have any symptoms. These warts can be treated with special medicine (not the same over-the-counter medicine used to treat warts on other parts of the body like the fingers). Herpes is caused by the virus herpes simplex, which comes in two forms. Herpes simplex virus type 1 (HSV-1) typically causes “oral herpes” and most often appears as cold sores around the mouth. HSV-1 isn’t technically an STI, although it can be contracted from a person with HSV-1 through kissing or oral sex. Most people with HSV-1 get it some way other than sexual contact, such as sharing a cup with an infected person, and it’s very common in childhood. Herpes simplex virus type 2 (HSV-2), on the other hand, is usually spread just through sexual activity, although it can also be passed to babies during a vaginal birth. It typically appears as blisters or sores on the genitals, although again some people may not have any symptoms. The blisters may go away after treatment with medication, but may come back during times of illness or stress. When we talk about someone “having herpes”, we’re most often talking about HSV-2, though not always.

The human immunodeficiency virus (HIV) produces different symptoms than HPV and HSV-2. The initial infection typically involves not warts or sores on the genitals, but flu-like symptoms such as fever, chills, fatigue, and a sore throat. Often these symptoms go away within a couple of weeks, and then the person may not have any symptoms for as many as 10–15 years (HIV.gov, 2022). Unfortunately, this means that people may unknowingly spread HIV to others during that time. Also, without treatment, the virus slowly destroys the body’s immune system, and the person eventually develops severe medical problems such as pneumonia, tuberculosis, dementia, and some types of cancers. Some of these are opportunistic infections, medical conditions that occur more frequently in people with weakened immune systems who can’t fight them off. An HIV-positive person who develops these types of medical problems is now said to have acquired immunodeficiency syndrome (AIDS), a late stage of HIV infection in which the body’s immune system is significantly weakened and susceptible to a wide variety of diseases.

A viral STI can’t be treated with antibiotics, and a person with HPV or HSV-2 will carry the virus for the rest of their life. They may need to take medication regularly to prevent or treat flare-ups. Similarly, a person with HIV will need medication lifelong to prevent the virus from continuing to multiply inside their body. With early and high-quality medical care, they can enjoy good health and quality of life for many years.

The incidence of STIs is unequal across the population. Non-Hispanic Black individuals make up only 12.6 percent of the U.S. population but account for 31 percent of chlamydia, gonorrhea, and syphilis cases. This high proportion is likely due not to a greater incidence of sexual behavior, but to lack of access to reproductive and sexual health care (CDC, 2024), typical for marginalized groups. For example, HIV is more common among men who have sex with men (CDC, 2021); in the early days of the HIV pandemic, the disease wasn’t taken seriously and people with HIV were treated poorly because both being gay and having a disease were stigmatized.

Diagnosing and treating STIs is crucial to avoid permanent health consequences. HPV is known to cause six types of cancer, including of the cervix, penis, and vagina (National Cancer Institute, 2023.) HPV can’t be eliminated from the body, but a person who knows they have it can get regular medical checkups to detect cancer early enough for treatment. Chlamydia, gonorrhea, and syphilis can all cause infertility, chronic pelvic pain, and complications in pregnancy such as premature birth. If untreated for decades, syphilis can damage the brain and produce blood clots, stroke, and dementia. Treatment for HIV works best if started early, and while people who are HIV-positive may not know for several years, testing is available and recommended.

The stigma associated with STIs—and sometimes with sexual activity in general—can prevent people from seeking treatment. Deciding to engage in sexual activity requires taking increased responsibility for monitoring your health, however, including getting regular STI testing and being honest with health care providers about behaviors and symptoms.

In recent years, treatments for HIV have dramatically improved meaning that most people with HIV can manage the virus through antiretroviral therapy (ART). ART involves taking medicines that allow people to get and stay at a level of virus suppression that helps them to stay healthy and means they will not transmit HIV to other during sexual intercourse (CDC, 2024).

Pregnancy in Early Adulthood

You learned earlier about the process and milestones of pregnancy and childbirth (Chapter 2 Genetic, Prenatal, and Perinatal Health). Pregnancy is exciting and welcome news for many (Figure 11.11), but not for all. “Unintended pregnancy” refers to any situation in which a person becomes pregnant without intending to.

In the United States, approximately 3.6 million people give birth each year, with 48.6 percent of these people being between the ages of 18–29 (Osterman et al., 2024). Determining how many of these pregnancies are unintended is challenging because many of them are likely to occur among people who aren’t married, and being a single parent is still associated with some stigma in many cultures. Therefore, people may not report this information thoroughly.

Figure 11.17 Pregnancy and parenthood are major life changes. (credit: “Pregnant woman” by Brit/nappy, Public Domain)

As you learned in Chapter 2 Genetic, Prenatal, and Perinatal Health, pregnancy causes many physical changes, which can be hard on the body during the pregnancy and postpartum period. Worldwide, maternal mortality is still a concern, with around 287,000 birth mothers dying in childbirth each year—most often in middle and lower income countries (World Health Organization, 2024). However, most pregnancy-related deaths can be prevented through effective prenatal and perinatal care (CDC, 2024) and the birth mother's body generally physically recovers from the pregnancy and delivery during the first couple months after delivery (Lopez-Gonzalez & Kopparapu, 2022). For those who decide to keep and raise a baby, becoming a parent is a significant transition that's expensive, emotionally challenging but often rewarding, and. time-consuming.

This is likely one of the reasons, we see a societal trend to delay parenthood until later in early adulthood or even in middle adulthood for those who choose to become parents. In addition, we have seen trends of more people choosing not to become parents often citing financial concerns (APA, 2024). Mothers in particular still take on a higher caregiving load in most families with small children and additionally face a high deal of societal pressure, often known as "mommy guilt" to bear the main responsibility of the child's wellbeing (Constantinou et al., 2020). This pressure can be present across family types including in particular single mothers and heterosexual couples, even when the couple has a high level of shared responsibility. While fathers take on much more caregiving responsibilities than was common in decades past in the U.S., mothers are still much more likely to reduce or leave the workforce than fathers (Heggeness, 2020).

Choosing to become a caregiver and starting a family can be a fulfilling part of an individuals identity. Planned parenting often brings psychological fulfillment and wellbeing, enjoyment of family socioemotional experiences, and can contribute to a person's sense of meaning in life (Chen et al., 2016). This can mean that for many becoming a parent can be another important part of identity formation and commitment, best facilitated by having social support, control over the choice to become a parent, and knowledge about parenting effectively (Chen et al., 2016; Piotrowski, 2020).

Parenthood can also affect the transition to adulthood. Becoming a parent is a very adult, and often rewarding, responsibility that can help define our identity. But in early adulthood it can also interfere with the achievement of identity tasks such as furthering an educational or training program and starting a career (Landberg et al., 2019) (Landberg et al., 2019). People may find an identity in becoming a parent, but it may also delay or prevent them from exploring other facets of their identity; of course, we can say the same about other choices we commit to.

Both STI and pregnancy prevention share some similar strategies, and some foundational elements. First, without completely avoiding sexual activity (known as abstinence), guaranteed prevention of STIs and pregnancy is nearly impossible. Thus, there is no truly “safe sex” and precautions instead can provide “safer sex.” When choosing a pregnancy or STI prevention method, it’s important to be aware of your health status and use good decision-making to determine what’s likely to work best for you and any partners.

Abstinence is often said to be the most reliable method for avoiding STIs and pregnancy (CDC, 2023). However, not everyone understands “abstinence” the same way. Some people consider abstinence to mean avoiding any kind of sexually-related contact, including oral sex and mutual masturbation. Others use this term only to mean avoiding penetrative intercourse (Byers et al., 2009; Hans & Kimberly, 2011). These varying definitions of this term can give different impressions about a person’s sexual activity and could put them at risk for contracting an STI. For example, a person who engages in oral sex but not intercourse could contract herpes while still considering themselves abstinent. When discussing abstinence, either in a personal conversation, a health-related setting, or a research context, it’s important to make sure you know how others define abstinence.

Other behavior-based STI prevention methods include being in a monogamous relationship, reducing one’s number of sex partners, and avoiding drug and alcohol use. Because drugs and alcohol can impair judgment, people who use substances are at higher risk of STIs because they may engage more often in risky sexual behaviors like unprotected sex or sex with multiple partners (Baskin-Sommers & Sommers, 2006; Kusunoki & Barber, 2020). There are also medications (both shots and pills) to reduce the chances of getting HIV. These medications are called pre-exposure prophylaxis (PrEP) and are meant to be taken on a regular basis—a similar strategy as birth control pills, but for preventing HIV and not pregnancy.

Apart from abstinence, condoms are the only method effective at preventing both pregnancy and STIs. Condoms are called a barrier method because they prevent exchange of bodily fluids. Another barrier method used for STI prevention is a dental dam, a thin piece of latex or polyurethane that’s placed over the vulva or anus prior to oral sex. Other barrier methods that are used as pregnancy prevention but not STI prevention include diaphragms, cervical caps, and contraceptive sponges. Each of these is inserted into the vagina prior to sex and work to keep semen from reaching the uterus. They’re also typically used with spermicide, a gel that kills sperm cells, increasing the effectiveness of pregnancy prevention. All of these barrier methods have to be placed before sex and removed afterward; they’re not left in place between sexual encounters. Removal should be done following the product’s directions or as advised by a health-care provider to optimize their effectiveness.

Some pregnancy prevention methods are hormone based. Birth control pills, contraceptive shots, and contraceptive implants each contain the synthetic hormone progestin, which prevents ovulation. Contraceptive shots and implants are long-lasting (3 months and 5 years respectively). Birth control pills must be taken daily, and medications like antibiotics can have contraindications that may make them ineffective.

Other methods of pregnancy prevention are more complex. An intrauterine device (IUD) is a small T-shaped device that’s inserted into the uterus via the vagina. It works by either preventing ovulation or reducing the movements of sperm. Unlike a diaphragm, an IUD can stay in place long-term (several years); however, it must be inserted and removed by a health-care provider. There are also surgical birth control methods.

Sexual Harassment and Sexual Violence

So far we've been talking about sexual activity as always consensual, relatively common, and hopefully enjoyable aspects of life in early adulthood. Unfortunately, some experiences fall outside of that: sexual harassment and sexual violence.

Any unwanted sexual activity that is forced on another person in any way without their consent is considered an act of sexual violence (National Sexual Violence Resource Center, 2010). Force can involve verbal, physical, or emotional behaviors, such as manipulation. Sexual violence may include assault, abuse, harassment, exploitation, public exposure, or stalking behaviors. Regardless of the type of sexual violence, all acts of sexual violence involve harm to another person. Sexual harassment is a broad term referring to a range of actions representing unwanted physical or verbal attention with a sexual basis. It most commonly involves behaviors that make a person uncomfortable and interfere with that person’s ability to engage in typical activities such as going to school, working, or participating in extracurricular settings, like a sports club or religious group. These behaviors don’t even have to be directed at a specific person to be considered sexual harassment. Repeatedly making negative comments about a specific gender or talking about sexual acts or fantasies could constitute sexual harassment even if it just occurred within earshot of a person who wasn’t directly included in the conversation. Sexual harassment often involves a power differential in that the harasser may be in a position of authority, such as a boss, teacher, or spiritual leader. However, this isn’t a requirement to define sexual harassment; it can occur among peers, such as among teammates or classmates. Some acts of sexual harassment, such as rape or unwanted touching, are also considered sexual assault. Sexual assault is defined as nonconsensual sexual contact. Consent must be explicitly given; “not saying no” is not the same as saying “yes”. A person who’s unconscious or too scared to refuse has not given consent. Neither has a person who’s unable to make informed decisions due to intoxication or cognitive impairment.