Psychology of Growing Up: When Do We Become Adults, and Who Remains a Child?

Growing up is a multifaceted transition from childhood to maturity, involving both biological transformations and psychological, social, and legal changes. Different cultures and societies may draw the line between “child” and “adult” in various ways. On one hand, there are biological markers like puberty and physical development; on the other, there is psychological maturity—emotional development, social responsibility, and self-awareness. Layered on top of these are the legal definitions of adulthood, which vary across countries, and cultural traditions that shape their own “rites of passage.”

In this article, we will examine the mechanisms of growing up in a holistic way—covering biology, law, culture, and personal self-identification. We will put a special focus on countries in the former Soviet Union (CIS) and the UAE, touching briefly on Western, Eastern, and African contexts, as well as the broader MENA region. Finally, we will analyze at what point society considers someone an adult and how that aligns—or conflicts—with each individual’s own sense of maturity.

Contents

Biological Stages of Maturation
Puberty and Physical Growth
Hormonal Shifts and Emotional Turbulence
Psychological and Social Maturation
Cognitive Development and Decision-Making
Emotional Maturity and Responsibility
Social Independence
Legal Criteria for Adulthood
Age of Majority Around the World
The UAE and MENA Perspectives
Other Legal Thresholds
Cultural Traditions and Coming-of-Age Ceremonies
Western Context
The Post-Soviet Space (CIS)
The Arabian Gulf, UAE, and the Broader MENA Region
East Asia
Africa, Latin America, and Beyond
Society and the Individual: When Do We Feel Like Adults?
Conclusion
Sources and Further Reading

Biological Stages of Maturation

Puberty and Physical Growth

The foundation of growing up lies in the biological changes that transform a child into an adult. Puberty (sexual maturation) is central to this process. Triggered by hormones, the body develops the ability to reproduce, secondary sex characteristics emerge, and physical growth accelerates (Puberty – Wikipedia). On average, girls enter puberty around ages 10–11 and complete it by 15–17, while boys enter at about 11–12 and complete it by 16–17 (Puberty – Wikipedia). Key milestones during puberty are the first menstrual period (menarche) for girls (approximately age 12.5) and the first ejaculation for boys (around age 13).

However, the biological process of maturing is not limited to the reproductive system. Brain development and the maturation of the nervous system continue well into the mid-20s. Research indicates that the prefrontal cortex—responsible for executive functions such as planning, impulse control, and complex decision-making—does not fully mature until around age 25 (Under the Hood of the Adolescent Brain | Harvard Medical School). As a result, even though adolescents are sexually mature by their mid-teens, full neurobiological readiness for adult responsibilities often comes later. Specialists from Harvard Medical School vividly describe the prefrontal cortex as “the last part of the brain to finish developing, well into the mid-20s,” thereby affecting a young person’s long-range planning and impulse management.

Hormonal Shifts and Emotional Turbulence

During adolescence, a surge in hormones—testosterone, estrogen, and others—fuels not only physical changes but also emotional volatility. The limbic system, which governs emotion and risk-taking, develops faster than the frontal lobes, which are responsible for executive control. This imbalance can explain the strong emotional responses and higher risk-taking behaviors often seen in teenagers (Under the Hood of the Adolescent Brain | Harvard Medical School). Over time, these biological mechanisms reach an equilibrium: by about age 20, physical growth and puberty wind down; by roughly age 25, the structural maturation of the brain is typically complete.

From a purely biological standpoint, then, “be coming an adult” is a gradual process. The body and brain “ripen” through adolescence and into early adulthood, rather than reaching full maturity overnight.

Biology lays the groundwork, but “adulthood” also implies psychological maturity and the ability to function independently within society. This includes cognitive development, emotional regulation, personal responsibility, and social competence. Below are the core elements.

Cognitive Development and Decision-Making

A key marker of adulthood is the capacity to make well-considered, autonomous decisions. Cognitively, this is closely tied to the development of abstract thinking and executive function in the brain. According to Swiss psychologist Jean Piaget, around ages 11–15, adolescents typically transition to the “formal operations” stage, enabling abstract reasoning. Modern neuroscience refines this view, noting that the ability to assess long-term consequences continues evolving into the mid-20s (Emerging Adulthood as a Critical Stage in the Life Course – NCBI Bookshelf).

By around 18, most people have a basic ability to reason like adults, but the adolescent brain remains more susceptible to stress and impulsive decisions (Under the Hood of the Adolescent Brain | Harvard Medical School). Maturity is therefore an ongoing cognitive process: teenagers gradually learn to make decisions more independently and responsibly, often honing strategic thinking as they move into their 20s. Rates of development are individual: some teenagers acquire a mature outlook early due to challenging life circumstances, while others may still feel unprepared for full independence at 25.

Emotional Maturity and Responsibility

Emotional growth is as critical as physical growth. Children often respond impulsively, lacking full mastery over their emotions. In contrast, adults generally exhibit better emotional regulation and greater empathy. Biologically, the “hormonal storm” of adolescence subsides in the early 20s, while life experience also helps shape emotional resilience.

A hallmark of emotional maturity is the acceptance of personal and social responsibility. Teenagers gradually learn to see the world not only through their own needs but also to consider the needs and feelings of others. Survey data from Russia, for example, show that people commonly define adulthood as the ability to take responsibility for one’s actions and support oneself financially (Когда человек становится взрослым? / ФОМ – Russian Public Opinion Research). Taking on responsibility—whether for one’s own livelihood, family, or significant decisions—is a traditional benchmark of adult identity.

Psychologists also emphasize the development of identity—an internal answer to “Who am I, and what is my place in society?” According to American psychologist Erik Erikson, the transition from adolescence to young adulthood is a stage of “identity vs. role confusion,” during which young people try out different roles and lifestyles. Successful resolution leads to a sense of inner stability: people who understand their values, goals, and can make independent decisions are well on their way to emotional adulthood.

Social expectations often lead to the stereotype that girls mature faster than boys. In Russia, 89% of those surveyed said they believe young women reach maturity earlier than young men (Когда человек становится взрослым? / ФОМ). Biologically, females do enter puberty earlier, and culturally they are sometimes expected to show more seriousness from a younger age. Still, individual upbringing and life experience are often more decisive than gender when it comes to true emotional maturity.

Social maturity manifests in attaining independence and fulfilling “adult” social roles. Children rely on their parents for almost everything—food, shelter, decision-making. Adults, by contrast, are considered fully autonomous members of society. The transition—covering teenage and early adult years—is typically marked by an expansion of rights and responsibilities.

Some standard milestones include managing one’s own finances, making decisions about education and work, and shifting from a dependent relationship with parents to a more equal footing. In traditional cultures, forming a family—marriage and childbearing—was historically the most definitive sign of adulthood. In the modern world, these milestones have become more fluid. For example, in many European-influenced societies of the mid-20th century, be coming an “adult” involved finishing school, starting a career, marrying, and having children—often by age 20–25. Today, those steps often occur later (4 Reasons Why You May Still Not Feel Like a Real Adult | Psychology Today). Nonetheless, financial independence and living arrangements remain key factors. A person is widely seen as “fully adult” once they can cover their own expenses, housing, and food without parental support (Когда человек становится взрослым? / ФОМ).

Psychologist Jeffrey Arnett, who studies “emerging adulthood,” found that young people commonly judge their own adulthood based on:

Accepting responsibility for themselves
Making independent decisions
Achieving financial independence

(Emerging Adulthood as a Critical Stage in the Life Course – NCBI Bookshelf)

Where any of these three pillars is missing—e.g., still living off parents—an individual may not fully “feel” like an adult, even at 18 or 20. Conversely, someone forced by circumstance to work full-time and support others from an early age may see themselves as an adult far sooner.

In short, psychological and social maturity is a gradual, multi-dimensional journey. It doesn’t arrive automatically on a specific birthday. Rather, it involves building mental, emotional, and practical skills—a process that often continues into one’s mid-20s and beyond.

Legal Criteria for Adulthood

Societies need clear boundaries to differentiate between childhood and adulthood in practical matters—voting, signing contracts, criminal liability, and so on. The legal age of majority serves this purpose, granting an individual the full set of adult rights and obligations. A person under this threshold is deemed a “minor” (child) and has limited legal capacity.

Age of Majority Around the World

Internationally, 18 is the most common age of majority. The United Nations Convention on the Rights of the Child defines a child as any person below 18 years old, unless a country’s laws set an earlier threshold (Convention on the Rights of the Child | OHCHR). Reaching 18 frequently confers full legal adulthood, as is the case in most CIS countries (Russia, Ukraine, Belarus, Kazakhstan, etc.) and many other nations. From this point on, young people typically gain rights like voting, marrying without special permissions, making binding financial deals, and driving vehicles.

But laws differ across the globe. In parts of the United States, people legally become adults at 18, yet restrictions on buying alcohol remain in place until 21 (Age of majority – Wikipedia). Historically, 21 was the standard age of majority in the U.S. (carried over from English common law), and although it was lowered to 18 in the 20th century, 21 still marks the legal drinking age and remains socially celebrated as a “milestone birthday” (Coming of age – Wikipedia).

In Japan, adulthood was traditionally recognized at 20, culminating in an annual “Coming of Age Day” (Seijin no Hi) each January to celebrate all those who turned 20 that year (Coming of age – Wikipedia). While Japan recently lowered the official legal threshold to 18 in 2021, cultural practices often lag behind legislative changes. Similarly, South Korea has long had a legal adult age of 19 (or 20 in traditional counting) and also organizes a Coming of Age ceremony in May, a ritual now somewhat more symbolic than strictly legal.

The UAE and MENA Perspectives

In some Middle Eastern legal systems, the age of full adulthood can be higher than 18. The United Arab Emirates (UAE), for instance, sets full legal capacity at 21 (What is the Legal Age Requirement for Property Ownership in the UAE? | Chambers). Individuals aged 18–20 in the UAE may be allowed certain rights—like marrying at 18—but remain under parental or judicial oversight for major financial transactions such as owning property or launching a business. Full legal autonomy commences at 21, reflecting both cultural family structures and certain interpretations of Sharia.

At the same time, the UAE’s minimum marriage age is 18, with the government emphasizing the protection of minors and prohibiting marriage before legal adulthood (Forced Marriage Overseas: Dubai – Tahirih). This distinction between “be coming of age” at 18 and gaining full capacity at 21 is an example of how MENA countries may differentiate between core adult rights (like marriage) and more complex financial or legal capacities.

Historically, the benchmark of 21 in many regions—including parts of the Middle East—can be traced to older legal frameworks, sometimes carried over from European or Roman law. In societies where extended family ties are strong and where higher education or specialized training is the norm, deferring full adult responsibility to 21 can make sense. At the same time, many MENA countries have been modernizing their legal codes and aligning them in part with global norms, including international standards like those from the ICC (International Chamber of Commerce) or the ISO (International Organization for Standardization), which promote coherent commercial and legal practices across borders.

Other Legal Thresholds

Legal definitions of adulthood do not always align neatly with other facets of maturity. For instance, in many jurisdictions, criminal liability begins partially around 14 or 15, with full accountability at 16 or 18. Age of sexual consent can be younger than 18 (16 in parts of Europe and some U.S. states). Meanwhile, alcohol purchase in some places requires being 21. These staggered age limits serve as gradual, protective measures—adolescents may have certain rights recognized while remaining restricted in areas deemed especially high-risk.

Legally, a person “becomes an adult” at the specific age set by their country’s laws, acquiring the associated rights and responsibilities overnight. Yet many 18-year-olds lack the real-world readiness those legal rights demand, just as there are under-18 individuals who shoulder adult responsibilities out of necessity. We will next explore how culture and tradition further shape the concept of “coming of age” across the globe.

Cultural Traditions and Coming-of-Age Ceremonies

In addition to biology and law, each culture defines its own social and symbolic demarcation between childhood and adulthood. From indigenous rites of passage to religious ceremonies and festive celebrations, these “coming of age” customs illuminate societal values and norms.

Western Context

Modern Western societies tend not to practice many formal initiations, but certain traditions persist. Among Jews, Bar Mitzvah for boys at age 13 and Bat Mitzvah for girls at age 12 mark religious accountability—“adults” in the eyes of Jewish law (13 Amazing Coming of Age Traditions From Around the World). In Catholic Christianity, confirmation is a sacrament undertaken in adolescence, signifying entry into full church membership.

Secular Westerners often celebrate turning 18 (the legal threshold) and 21 (a cultural vestige in the U.S.), while high school graduation around 17–18 also serves as a common rite of passage. Nonetheless, modern adulthood in these societies is more diffuse, with many people delaying marriage or stable careers until their late 20s or even 30s (When Do You Become an Adult? – The Atlantic).

The Post-Soviet Space (CIS)

In many former Soviet republics, traditional coming-of-age rituals have largely disappeared, replaced by civic or legal markers. One notable example is receiving a passport at age 14 in Russia, Kazakhstan, and others, symbolizing a first step toward adult status. Although a 14-year-old is still considered a minor, they gain partial legal capacity—such as the right to limited employment and certain legal responsibilities.

Another watershed event is completing secondary education around age 17, often culminating in a “graduation ball” that marks the transition to adult life (work or college). For young men, mandatory military service at 18 can also function as an informal initiation. In some Caucasian or Central Asian communities, cultural customs—like demonstrating one’s ability in labor or completing a circumcision ceremony in certain Muslim traditions—have historically underscored a youth’s readiness for adult roles. Marriage (often in the early 20s) remains a strong social signal of full adulthood.

The Arabian Gulf, UAE, and the Broader MENA Region

Throughout the Arab world, Islamic norms profoundly shape concepts of adulthood. Religious adulthood (baligh) starts with puberty—once a boy has his first ejaculation or turns 15 (by some interpretations), and once a girl experiences menarche (but not later than 17 by certain traditions). At this point, they are expected to follow the tenets of Islam—praying, fasting, and bearing religious responsibility (Совершеннолетие — Википедия, Russian-language source).

Socially, however, MENA cultures distinguish between religious maturity and adult independence. In more traditional families—such as in the UAE—teens usually remain under parental guidance, and the true hallmark of adulthood often comes with marriage and the ability to provide for a family. Young people frequently live at home until marriage, at which point they either set up their own household or assume a new role within the family compound. Government policies in the Gulf have evolved to protect young citizens (for instance, by regulating early marriage and encouraging higher education). While a devout Muslim teen may be seen as religiously “adult,” they may not be socially viewed as fully mature until at least 21, or until they have completed higher education or begun a professional career.

East Asia

East Asian cultures also feature distinct coming-of-age traditions. Japan’s Coming of Age Day (Seijin no Hi), historically at age 20, celebrates new adults at municipal ceremonies, where young women often wear formal furisode kimonos (Coming of age – Wikipedia). While Japan legally redefined adulthood at 18 in 2021, many cultural practices—like the ceremonial day—still revolve around the age of 20. In South Korea, a Coming of Age ceremony also used to be held around 19 or 20, sometimes involving the symbolic wearing of traditional garments or hats. Modern Chinese culture occasionally revives older customs—like the capping ceremony (for men at 20) or hair-pinning (for women at 15)—but today, 18 is generally accepted as the legal benchmark.

Africa, Latin America, and Beyond

In various African societies, rigorous initiation rituals abound. Among the Xhosa in South Africa, for instance, a 17–18-year-old boy undergoes Ulwaluko, a seclusion period in the wilderness and traditional circumcision without anesthesia, rejoining the community as a “man” afterward (Ulwaluko – Wikipedia). Similar rites among certain Kenyan and Tanzanian communities highlight physical endurance and bravery (Circumcision and its effects in Africa – PMC).

In Latin America, the quinceañera—celebrated at a girl’s 15th birthday—is a large-scale festivity marking her transition into young womanhood. While it does not confer official legal privileges, it is culturally significant in countries like Mexico, Cuba, Colombia, and others (Coming of age – Wikipedia). For some families, it parallels a “debutante ball” and underscores the beginning of social responsibility in a traditional community setting.

In short, cultural boundaries can mark adulthood at widely varying ages—sometimes as early as 13 in religious contexts, sometimes as late as the early 20s under modern legal frameworks. Whether the focus is on passing a test of endurance, celebrating with friends and family, or fulfilling a religious duty, every society has symbols to signal a new stage of life.

Society and the Individual: When Do We Feel Like Adults?

Having examined biological, psychological, legal, and cultural dimensions, we now face the ultimate question: when does a person truly “feel” like an adult? Does that moment align with turning 18, or 21, or some ceremonial rite? Individual experiences differ significantly. Many people report they did not suddenly feel “grown up” at 18 or even 21 (Fear of Adulting: I’m 21 But I Still Don’t Feel Like an Adult). Contemporary psychologists identify a stage known as “emerging adulthood,” roughly spanning the ages of 18–25 (When Do You Become an Adult? – The Atlantic). It is a transitional period of exploration—where an individual is no longer a child yet not entirely anchored in adult roles.

In surveys, people of various ages give diverse answers about when they first felt like an adult. One person may say 16, when they had to work and help support the family. Another may say 30, upon having a child. On average, early 20s are often named as the point of feeling more mature—though many add, “not in every aspect.”

There are multiple reasons for this. First, modern adulthood requires juggling numerous roles—student, professional, partner, caregiver. One may have legal rights without feeling equipped for real-world responsibilities. Second, social norms have shifted in many countries. People are marrying later, pursuing advanced degrees, and sometimes staying dependent on parents well into their 20s. Third, personality and upbringing shape the speed of maturation. A teenager who has to handle serious responsibilities quickly may “grow up” fast, while a 25-year-old living at home under parental care may feel more like a child.

Psychologically, many of us also form unrealistic childhood images of adulthood as an all-knowing, all-capable state. Hitting your 20s or even 30s and realizing you are not magically “all-knowing” can perpetuate a sense of not being a “real” adult (4 Reasons Why You May Still Not Feel Like a Real Adult | Psychology Today). In truth, growth is lifelong, with shifting developmental tasks at each stage. The real hallmark of adulthood often appears when a person confronts tangible responsibilities—such as taking on a demanding job or be coming a parent.

Cultural norms also play a big role. In traditional rural parts of Central Asia or North Africa, a 16-year-old who contributes significantly to household duties or is prepared for marriage might well be seen (and see themselves) as an adult. Conversely, in large cities like Moscow or Dubai, a 16-year-old high school student is more likely to be treated as a dependent adolescent. Socioeconomic factors matter too: in struggling economies, adolescents may be forced to grow up earlier out of necessity.

Generational differences further color these perceptions. Older generations often accuse the young of “still being kids at 25,” while young people argue that the complexity of modern life delays conventional markers like stable employment or marriage. Opinion polls in Russia reveal a divide: some believe today’s youth mature faster due to greater access to information, while others see them as maturing more slowly (Когда человек становится взрослым? / ФОМ). There is no simple verdict; adulthood has become a more variable concept.

Psychologists caution that lacking certain achievements at 18 or 20 does not necessarily mean someone is “still a child.” True maturity unfolds over time as a person masters responsibility, self-regulation, and the capacity to care for others. Eventually, nearly everyone reaches a point where these things fall into place—though it may be triggered by widely different life events or ages.

Conclusion

Growing up involves a complex interplay of biological, psychological, cultural, and legal factors. There is no single universal moment when a child “magically” becomes an adult—rather, it happens in stages. Biologically, we reach sexual maturity in our mid-teens but only complete brain development in our mid-20s. Legally, many countries choose 18 as the bright line for adulthood (others pick 21). Culturally, societies recognize the transition through an array of rites, tests, and celebrations—some formal, others more symbolic.

Above all, adulthood is not just about age but also about mindset. A person may be legally an adult at 18 but not genuinely feel like one until they accept responsibility for themselves—financially, emotionally, and socially. Ideally, by the time the law grants adult rights, the individual has the psychological readiness to handle them. However, maturity arrives at different paces for different people.

In both CIS countries and the UAE—despite diverse traditions—adulthood is commonly associated with the capacity to be responsible for oneself and potentially for others, to make autonomous decisions, and to live independently. Legal age limits provide a clear “minimum threshold,” but true adulthood is reached when someone steps into adult roles: a professional, a spouse, a parent, or simply a self-reliant individual.

We can imagine the path to adulthood as an intricate system of “gears”: biology sets key processes in motion; psychology refines decision-making and emotional control; societal laws offer official markers; and culture provides rituals for symbolic recognition. Once all these gears align, the sense of being an adult “clicks” into place—though for some it happens early, for others it takes time. Even as modern life blurs boundaries between childhood and adulthood, this journey remains one of the most important and transformative phases of human development, shaping who we are and how we chart our future.

Mechanisms of Growing Up: When Does a Person Become an Adult, and Who Is Considered a Child?