Yes, it is possible for a girl to have a penis. This can happen in two distinct ways: a girl may be transgender, meaning she was assigned male at birth but identifies and lives as female, or she may have been born with an intersex condition that caused her body to develop genitalia that don’t match her chromosomes or internal anatomy. Both situations are well-documented in medicine and occur more often than most people realize.
Transgender Girls and Gender Identity
Sex assigned at birth is based on a baby’s external anatomy. Gender identity is a person’s internal sense of being male, female, or something else. For most people, these align. For transgender people, they don’t. A transgender girl has a male body, including a penis, but her gender identity is female.
This isn’t a new phenomenon or a cultural trend. Gender identity has a biological basis, and transgender identities have been recognized across cultures for centuries. A transgender girl may or may not pursue medical steps later in life, such as hormone therapy or surgery. Regardless, she is a girl with a penis unless and until she chooses otherwise.
Intersex Conditions That Cause This
Some people are born with bodies that don’t fit neatly into typical male or female categories. The United Nations estimates that up to 1.7 percent of the population is born with intersex traits, making it roughly as common as red hair. Several specific conditions can result in a girl having a penis or genitalia that closely resemble one.
Congenital Adrenal Hyperplasia
This is the most common cause. A baby with XX chromosomes (the typical female pattern), ovaries, a uterus, and fallopian tubes can be born with external genitalia that look male. During fetal development, the adrenal glands overproduce hormones that get converted into testosterone and related androgens. These hormones cause the labia to fuse together and the clitoris to enlarge significantly, sometimes enough to resemble a penis. Internally, the reproductive anatomy is female. The child may be assigned male at birth based on appearance alone, raised as a boy, and only later discover her female internal anatomy.
5-Alpha Reductase Deficiency
This condition works in the opposite direction and can be particularly dramatic. Children with XY chromosomes are born with genitalia that appear female and are raised as girls. Then, at puberty, a surge in testosterone triggers changes: the voice deepens, muscle mass increases, and the genitalia grow to resemble a typical penis and scrotum. These children were living as girls and, in some cases, continue to identify as female after these changes. In other cases, they shift to a male identity. The condition is caused by a missing enzyme that normally converts testosterone into a more potent form needed for male genital development before birth.
Androgen Insensitivity Syndrome
In partial androgen insensitivity syndrome, a person with XY chromosomes has cells that only partially respond to male hormones. The result can be genitalia anywhere on the spectrum, from typically female to typically male, including combinations of both. Some of these individuals are raised as girls and identify as female, while having genital anatomy that includes features usually associated with males. The degree of insensitivity varies widely from person to person because of differences in how the androgen receptor gene is altered.
Other Causes
Rarer scenarios include a mother being exposed to male hormones during pregnancy, whether from hormone-producing ovarian tumors or external testosterone. A condition called aromatase deficiency, where the enzyme that converts male hormones into female hormones doesn’t work properly, can also cause a chromosomally female child to develop male-appearing genitalia. This one sometimes goes unnoticed until puberty, when the child begins developing male physical characteristics.
How Sex Gets Assigned at Birth
Doctors assign sex based on what they see when a baby is born. In most cases, external anatomy lines up with chromosomes and internal organs. But intersex conditions show that external appearance can be misleading. A baby who looks male on the outside may have XX chromosomes, ovaries, and a uterus. A baby who looks female may have XY chromosomes and internal testes. The assignment happens in seconds, but the biology underneath can be far more complex.
When a baby is born with genitalia that don’t clearly fit either category, doctors may run chromosome tests, hormone panels, and imaging to understand the full picture. Historically, surgeons often operated on intersex infants to make their bodies conform to one sex or the other, sometimes without full parental understanding of the implications. This practice has become increasingly controversial. A review of U.S. legislation from 2021 to 2024 found that laws restricting gender-related medical care for transgender minors often included explicit exceptions allowing surgical “normalization” of intersex infants, raising questions about bodily autonomy and the right of individuals to make decisions about their own bodies.
Why the Answer Isn’t as Simple as It Seems
The question “can a girl have a penis” assumes that bodies come in two clean categories. Biology is messier than that. Chromosomes, hormones, internal organs, and external anatomy usually align, but they don’t have to. Each of these develops through separate biological pathways, and disruptions at any stage can cause them to diverge.
A person’s sense of being a girl doesn’t depend on any single body part. For transgender girls, identity and anatomy diverge from the start. For intersex individuals, the body itself contains a mix of traits that challenges simple classification. In both cases, a girl can have a penis, and neither situation is as rare as most people assume.