Tomboyism is one of the most studied aspects of childhood gender-typed behavior, and research consistently treats it as a common, normal part of development. Retrospective surveys suggest that more than half of adult women recall being tomboys as children, a figure high enough to make it arguably the norm rather than the exception. What makes the topic interesting is not just how many girls identify this way but the surprisingly tangled web of biology, family environment, and cultural framing that shapes it.
What Counts as a Tomboy
Researchers and the general public mostly agree on the basics: a tomboy is a girl who gravitates toward activities, toys, and play styles that are stereotypically associated with boys. Across multiple generational cohorts, adults who recalled being tomboys pointed to participation in male-labeled sports, rough-and-tumble play, and playing with male-labeled toys as the defining features of the experience. That consistency across generations is worth noting, because the specific activities considered “masculine” have shifted over time, yet the underlying pattern of crossing into the other group’s territory stays recognizable.
One nuance that often gets lost in casual conversation is that tomboyism is not simply a rejection of femininity. A study of self-identified tomboys and non-tomboys found that the two groups did not differ in how much they liked feminine activities or in the number of feminine activities they enjoyed. What set tomboys apart was greater interest in masculine activities on top of their typical engagement with feminine ones.1PubMed. Congruence between gender stereotypes and activity preference in self-identified tomboys and non-tomboys In other words, tomboys tend to have broader interests rather than swapped interests. They are adding to their repertoire, not replacing it.
A separate study that recruited tomboys between the ages of four and nine and compared them with their sisters and brothers found that on measures of playmate preference, sex-typed activities, and gender identity, tomboys scored substantially more masculine than their sisters but generally less masculine than their brothers.2PubMed. Who are tomboys and why should we study them? That in-between positioning captures something essential about the phenomenon: tomboyism is a matter of degree, not an either/or category.
Prenatal Hormones and the Biological Case
One of the strongest lines of evidence connecting biology to gender-typed play comes from studies of prenatal testosterone. Researchers have measured testosterone levels in amniotic fluid during pregnancy and then followed up with the children years later. One such study found that higher fetal testosterone was positively related to male-typical play scores in both boys and girls, providing direct evidence that hormone exposure before birth influences the kinds of play children prefer.3PubMed Central. Fetal testosterone predicts sexually differentiated childhood behavior in girls and in boys
Some of the most compelling data come from girls with congenital adrenal hyperplasia (CAH), a condition in which the adrenal glands produce unusually high levels of androgens starting before birth. Girls with CAH consistently show increased male-typical behavior and toy and playmate preferences compared to unaffected girls.4PubMed Central. Prenatal androgen exposure and children’s gender-typed behavior and toy and playmate preferences Because these girls are raised as girls and socialized as girls, the pattern is hard to explain without acknowledging a hormonal contribution.
The picture is not perfectly clean, though. A 2023 study that measured early prenatal sex steroids and then assessed children’s play behavior at age four found no associations between testosterone levels and play scores in either boys or girls.5PubMed. Early prenatal sex steroids and sex-typed play behavior at 4 years of age Methodological differences likely explain part of the discrepancy: the timing of hormone measurement, the specific assay used, and the age at which behavior is assessed all matter. The takeaway is that prenatal hormones are clearly part of the story but not the whole story.
Primate Parallels
If tomboyish play preferences were purely a product of culture, you would not expect to see anything similar in other species. But you do. When researchers gave wheeled toys and plush toys to a troop of rhesus monkeys, males showed a consistent and strong preference for the wheeled toys, while females showed greater variability in their preferences. The difference in preference between males and females was statistically significant, and the researchers noted that these preferences developed without any gendered socialization from humans.6PubMed Central. Sex differences in rhesus monkey toy preferences parallel those of children
The observation extends beyond the lab. In a long-running field study of wild chimpanzees, juvenile females carried sticks more often than males did, in a pattern that resembled doll play. This sex difference could not be chalked up to females simply using objects more than males, because several other types of object use, including weapon use, were actually male-biased.7Current Biology. Sex differences in chimpanzees’ use of sticks as play objects resemble those of children The implication is that at least some sex-typed play preferences have deep evolutionary roots, and that the variability seen in some female primates parallels the kind of variability seen in human girls, some of whom lean heavily toward “masculine” play.
Family Environment and Social Learning
Biology sets the stage, but family dynamics also influence how the script gets read. One study of parent-child factors in girls’ gender-role socialization found that mothers of tomboys were more likely to have been tomboys themselves and to accept tomboyish behavior in their daughters.8Journal of the American Academy of Child Psychiatry. Parent-Child Factors in Gender Role Socialization in Girls That finding is consistent with a social learning explanation: a mother who enjoyed climbing trees and playing sports as a kid is more likely to encourage those activities in her daughter, or at least less likely to discourage them.
Disentangling genes from modeling is tricky here, because a mother who was a tomboy shares both her DNA and her attitudes with her daughter. The transmission could be biological, social, or most likely both. What the research makes clear is that parental attitudes toward gender-typed behavior matter. A girl with a modest biological predisposition toward rougher play will have very different outcomes depending on whether her family rewards or punishes that behavior.
How Much Is Heritable
Twin studies help tease apart genetic contributions from environmental ones. A study of Finnish twins found that variation in childhood gender-atypical behavior was partly due to genetics, with the rest explained by non-shared environmental effects, meaning the unique experiences each twin has rather than the family environment they share.9PubMed. Common genetic effects of gender atypical behavior in childhood and sexual orientation in adulthood: a study of Finnish twins A separate large twin study estimated the heritability of childhood gender typicality at roughly a third, the highest of the traits examined.10PLoS ONE. Genetic and Environmental Influences on Female Sexual Orientation, Childhood Gender Typicality and Adult Gender Identity
A heritability of around a third means genes account for a meaningful chunk of why some girls are tomboys and others are not, but it also means roughly two-thirds of the variation comes from environmental factors. And “environmental” in this context includes prenatal hormone exposure, not just how a child is raised. The shared family environment, such as parenting style and household norms, typically accounts for a surprisingly small portion once genetics and non-shared environment are included. That fits with the common observation that siblings growing up in the same household can differ dramatically in how gender-typical their behavior is.
Why Society Tolerates Tomboys More Than “Sissies”
There is a striking asymmetry in how cultures respond to gender nonconformity in children. A girl who wants to play football gets a label, “tomboy,” that carries relatively little stigma and is often considered positive. A boy who prefers dolls and dress-up gets a far harsher social reception. Research confirms this gap: one study found that “tomboy” was generally considered a positive label, while gender-nonconforming boys received much less favorable evaluations. In a follow-up, gender-nonconforming girls were rated as neither particularly likable nor dislikeable and neither competent nor incompetent, reflecting ambivalence rather than outright rejection.11PubMed. Sissies, Mama’s Boys, and Tomboys: Is Children’s Gender Nonconformity More Acceptable When Nonconforming Traits Are Positive?
Several explanations have been proposed for this double standard. One is that masculine traits and activities are simply valued more highly in most societies, so a girl who “moves up” toward them is seen as ambitious, while a boy who “moves down” toward femininity is seen as losing status. Another explanation centers on the rigidity of male gender norms: there is less room for boys to deviate before social punishment kicks in. Whatever the cause, the practical effect is that tomboyism occupies a culturally protected space that boys’ gender nonconformity does not. That protection may be eroding in some communities, though, as debates about gender identity make any childhood nonconformity feel more politically charged to parents and educators.
Tomboyism and Adult Sexual Orientation
One of the most persistent questions about tomboys is whether tomboyism predicts anything about adult sexual orientation. The research here is consistent in direction but limited in predictive power. A study comparing heterosexual, bisexual, and lesbian women on recalled childhood experiences found that lesbian women more often recalled male-stereotypic childhoods, while heterosexual women recalled female-stereotypic ones. Using four childhood attributes, including being considered a tomboy, researchers could distinguish heterosexual from lesbian women with about 80 percent classification accuracy.12PubMed. Differences between heterosexual, bisexual, and lesbian women in recalled childhood experiences
This association appears to hold across cultures. A 2024 study of Iranian adults found that women attracted to other women recalled behaving in a less female-typical and more male-typical manner during childhood compared to women attracted to men. The authors framed childhood sex-atypicality as a “normative developmental precursor” of same-sex attraction that shows up across Western and non-Western cultures alike.13PubMed. Association of Recalled Childhood Sex-Typed Behavior with Sexual Orientation and Gender Identity in Iranian Adult Males and Females
But it is important to read these findings the right way. Most tomboys grow up to be heterosexual. The correlation works better in reverse: when you survey lesbian adults and ask about their childhoods, tomboyism shows up disproportionately. When you survey tomboy children and follow them forward, most of them end up across the full spectrum of sexual orientations, with heterosexuality being the most common outcome. Tomboyism is a weak predictor of any individual girl’s future orientation, even though it shows up as a group-level statistical association. The twin study data hint at why: childhood gender typicality and adult sexual orientation share some genetic influences, but they are substantially independent traits, each shaped by its own mix of factors.14PubMed. Common genetic effects of gender atypical behavior in childhood and sexual orientation in adulthood: a study of Finnish twins
Athletics, Self-Esteem, and Protective Factors
Given that tomboyism is so common and generally socially tolerated, you might expect it to have no particular psychological costs. The reality is a bit more complex. Two studies examining the relationship between tomboy self-identification and self-esteem found that greater identification as a tomboy during childhood was associated with lower current self-esteem, but only among women who were less athletic. Tomboys who were highly athletic had high levels of self-esteem, comparable to non-tomboys.15Child Development Research. The Role of Athletics in the Self-Esteem of Tomboys
This makes intuitive sense. A girl who enjoys rough play and competition but never gets channeled into a sport may feel like an outsider without a clear social niche. A girl with the same inclinations who joins a soccer team or a swim squad gets a ready-made community that rewards exactly the traits she already has. Athletics provides a socially validated arena for physical competitiveness and toughness, and that validation appears to buffer against any self-esteem costs of not fitting the conventional feminine mold. For parents of tomboyish girls, the practical takeaway is straightforward: organized sports can be genuinely protective.
Tomboy Chic and the Fashion Industry
The word “tomboy” has a second life in popular culture, particularly in fashion, where “tomboy chic” periodically surges as a trend. An analysis of this phenomenon traced how fashion magazines, daytime television, and online advice sites celebrate a specific version of tomboyish style while simultaneously framing the underlying identity as delayed maturation in need of an intervention. The author argued that this re-fashioning of tomboy identity as “style-over-substance” jeopardizes an important outlet for genuine gender rebellion, turning something meaningful into an aesthetic choice any woman can put on or take off.16PubMed. Tomboy chic: re-fashioning gender rebellion
The tension here is real. On one hand, the normalization of masculine-coded clothing and attitudes for women could be seen as progress: the boundary of what is acceptable for women to wear and do keeps expanding. On the other hand, when tomboyism gets reduced to a fashion trend, the experiences of girls who genuinely feel more comfortable in male-typical play and social roles get flattened into a consumer identity. The childhood experience of being a tomboy, with its blend of hormonal predisposition, family dynamics, and personal temperament, is a different thing from an adult woman choosing to wear a blazer and sneakers.
Brain Structure and the Masculinity-Femininity Continuum
Neuroscience has begun exploring whether self-reported gender identity and expression map onto measurable brain differences. One study examining sex versus gender associations with brain structure found that, in females, higher femininity scores were linked to thicker prefrontal cortical regions, while in males no such association appeared. Independent of sex, people scoring higher on a masculinity-femininity continuum showed thicker cortical tissue in several frontal areas, including the superior frontal cortex and portions of the middle frontal cortex. These are regions broadly involved in decision-making and social behavior.
This kind of finding is at an extremely early stage, and it would be a mistake to conclude that tomboy brains “look different” in any clinically meaningful way. Brain imaging studies often have small samples, and the relationship between cortical thickness and any specific behavior is far from direct. What the research does suggest is that the psychological continuum between masculine and feminine is not purely a social construct floating above the brain; it has some structural correlates. Whether those correlates are causes, consequences, or just passengers alongside the behavior remains an open question.
The Prevalence Puzzle
If more than half of adult women recall being tomboys, is tomboyism even a distinct category, or is it just normal variation in girlhood? This is a genuine conceptual problem for researchers. Part of the issue is definitional: the threshold for calling yourself a tomboy varies enormously. Some women mean they preferred jeans over dresses; others mean they exclusively played with boys, refused dolls, and fought constantly. Those are very different levels of gender nonconformity, and lumping them together inflates the prevalence numbers.
The research community has handled this by moving toward continuous measures rather than yes-or-no labels. Instead of asking “Were you a tomboy?” and getting a binary answer, instruments like the Pre-School Activities Inventory place children on a spectrum from strongly feminine-typical to strongly masculine-typical. On that kind of measure, girls with CAH cluster toward the masculine end, and most girls cluster toward the feminine end, with a wide and well-populated middle. The girls who would colloquially be called tomboys tend to be in the upper-middle range, not at the extreme. The extreme end is rarer and more likely to involve the kinds of biological influences, like atypical prenatal hormone exposure, that researchers can actually trace.
For practical purposes, the broad cultural category of “tomboy” captures a wide swath of normal childhood behavior. The narrower research category, the one that predicts anything about biology or later development, focuses on girls whose play preferences are consistently and substantially more masculine than their female peers. That distinction matters when interpreting any of the findings described above: the statistical associations with prenatal hormones, genetics, and adult orientation are stronger when the definition of tomboyism is stricter.