By Dr. Medicore, Sex and Sexology

Sexual behavior is a fundamental aspect of human life, varying widely across cultures, age groups, and over time. Understanding these patterns—ranging from solo masturbation to same‑sex activities—not only illuminates how societal norms and technologies shape intimacy, but also highlights potential health risks and benefits. Drawing on large-scale surveys from the past decade, this article compares how adolescents and adults engage in various sexual practices in different countries and explores associations with clinical outcomes.

Methodological Considerations

Most data come from self‑report surveys with nationally representative samples. In the United States, the National Survey of Sexual Health and Behavior (NSSHB) captured detailed information on both adolescents (ages 14–17) and adults (18+) in 2009 and again in 2018, allowing longitudinal comparisons [link.springer.com]. For adolescents, the Youth Risk Behavior Surveillance System (YRBSS) provides biennial data on U.S. high school students’ experiences, including sexual initiation and partners’ sex, up to 2023 [cdc.gov]. Comparable national surveys exist in other regions, such as the Korean Research Institute of Sexuality’s studies in South Korea and the UK’s National Surveys of Sexual Attitudes and Lifestyles (Natsal).

Solo Masturbation Trends

Adolescents

In the U.S., solo masturbation among 14–17‑year‑olds decreased from 2009 to 2018: adolescents reporting any recent solo masturbation fell by roughly 10 percentage points over that period [link.springer.com]. Internationally, similar declines have been noted. In South Korea, only 15.2% of female and 49.9% of male high school students reported ever masturbating, despite 70% of females acknowledging it as natural.

Adults

Among U.S. adults, solo masturbation also decreased between 2009 and 2018, particularly among men: the proportion of adults reporting no partnered intercourse rose from 24% to 28%, and solo practices declined slightly in tandem with other sexual behaviors. European studies, such as the 2021 Natsal-4 pilot in Britain, suggest that roughly 60% of adults report masturbating at least monthly, with higher rates in younger cohorts.

Partnered Masturbation

Adolescents

Partnered masturbation among U.S. adolescents has declined alongside solo behaviors, dropping by approximately 8 percentage points in the past decade. Data from northern European countries mirror this trend, with fewer teens engaging in non‑coital partnered activities than two decades ago.

Adults

In the 2018 NSSHB, adults were less likely to engage in partnered masturbation compared to 2009, reflecting broader decreases in partnered sexual repertoires among both genders (e.g., declines in combined oral and manual stimulation). However, adults with higher relationship satisfaction reported partnered masturbation as a critical component of intimacy in qualitative studies.

Oral Sex (Giving and Receiving)

Adolescents

In the U.S., about half of 15‑ to 19‑year‑olds have tried oral sex, but oral encounters among younger teens (14–17) decreased by nearly 8% from 2009 to 2018. Globally, UK data show that 70% of 16‑ to 24‑year‑olds have had oral sex, with rising comfort but also concerns about emotional well‑being among teen girls.

Adults

Oral sexual activity remains common in adults worldwide: in the U.S., roughly 80% of adults report giving and receiving oral sex in the past year, with slight declines in frequency among older adults. Similar rates are seen in Australian and Canadian surveys, though cultural norms influence reporting.

Vaginal Intercourse

Adolescents

According to YRBSS 2023, 30% of U.S. high school students have ever had vaginal intercourse, a modest decline from 34% in 2009, with later initiation and fewer recent encounters noted in 2021 data [cdc.gov]. Internationally, western European teens report comparable initiation ages (16–17 years), while in parts of Asia and Africa, cultural taboos and schooling patterns lead to lower prevalence in adolescence.

Adults

Among U.S. adults, past‑year vaginal intercourse frequency decreased slightly from 2009 to 2018, with more adults reporting no vaginal intercourse (28% vs. 24%). In contrast, countries like Sweden and the Netherlands maintain higher adult coital frequencies, reflecting normative acceptance of sex across the lifespan.

Anal Intercourse

Adolescents

Anal intercourse among adolescents remains relatively rare but has shown slight declines across the past decade. In the U.S., fewer than 5% of 14–17‑year‑olds report ever having anal intercourse, down from around 7% in 2009.

Adults

Anal sex has gained visibility among adults, with about 20% of U.S. adults reporting ever trying anal intercourse by age 45 in recent surveys. Rates vary by country: higher in urbanized Western nations (up to 30%) and lower in regions with stronger traditional taboos.

Same‑Sex Sexual Behaviors

Adolescents

The 2023 YRBSS indicates that 3.0% of U.S. high school students report same‑sex only contacts and 5.1% both‑sex contacts, with the remainder reporting opposite‑sex partners or no sexual contact. These proportions have increased modestly since 2019, reflecting greater openness and self‑identification among LGBTQ youth.

Adults

Adult same‑sex experiences vary widely: in the 2018 NSSHB, approximately 8% of adults reported same‑sex attractions or behaviors, with younger cohorts (18–29) twice as likely as those over 50 to report such experiences. In countries with legal equality, rates tend to be higher due to reduced stigma.

Health Outcomes and Clinical Risks

Sexually Transmitted Infections (STIs)

• Adolescents: Declining intercourse rates have coincided with stagnant STI rates among U.S. teens; HPV and chlamydia remain concerns, especially with reduced condom use among some subgroups.

• Adults: A resurgence of syphilis and gonorrhea has been observed in several Western countries since 2015, correlating with decreased condom use in both vaginal and anal intercourse.

Unintended Pregnancy

Reduced adolescent vaginal intercourse and increased contraceptive use have led to declines in teen pregnancy in the U.S. (down by 50% since 2010) and similar trends in Europe, though rates remain higher where comprehensive sex education is limited.

Mental and Emotional Health

Solo masturbation and partnered sexual activities are generally linked to positive sexual well‑being for adults, but teens engaging in oral or vaginal sex without comprehensive education report higher rates of regret and lower self‑esteem (especially girls).

Sociocultural Influences

Cultural, religious, and educational contexts profoundly shape sexual behaviors. Countries with comprehensive, inclusive sex education (e.g., Netherlands, Sweden) report earlier but safer initiation and lower STI/unintended pregnancy rates. Conversely, in regions with restrictive education policies, adolescents often turn to online pornography—raising concerns about distorted expectations and risk behaviors.

Conclusion

Over the past decade, many countries have witnessed declines in both solo and partnered sexual behaviors among adolescents, while adults show more nuanced shifts—declining coital frequency but stable or evolving repertoires. Health outcomes mirror these trends: reduced teen pregnancy but persistent STI challenges. Embracing comprehensive, culturally sensitive education and promoting open dialogue remains key to supporting healthy sexual development and minimizing clinical risks across all age groups and regions.

Dr. Medicore is a journalist who writes on health issues under a pseudonym. 

Note: This article draws on data from the National Survey of Sexual Health and Behavior (2009–2018), CDC’s Youth Risk Behavior Surveillance System (2019–2023), and national studies in South Korea and Europe.