If you've always believed you were a woman… and your chromosomes say otherwise

Intersex & Variations in Sexual Development: Understanding It Simply

The human body can sometimes surprise even the most experienced doctors.

Some people are born with sexual characteristics (chromosomes, gonads, genitalia, or hormones) that do not fit neatly into the classic “male” or “female” categories. These are known as variations in sexual development (VSD), or intersex traits. These situations are more common than many realize—about 1 in 150 births shows a mild variation, and 1 in 5,000 to 10,000 a more significant one.

In this article, I explain, in simple terms, the main known forms, their causes, their characteristics, and what they can mean for fertility.

I also share a notable clinical experience that shows how surprising nature can be—even for doctors.

I once met a patient who had grown up and lived her entire childhood and adolescence as a girl. Everything appeared perfectly female, and she never had reason to doubt her bodily identity.

She was referred for a planned surgical procedure, initially intended to correct what was thought to be a malformation of the vagina or hymen. As a precaution, we performed a genetic analysis, and the results were astonishing: the patient was genetically male (XY).

The reason for her feminine appearance was a genetic defect in the androgen (testosterone) receptors, which prevented the visible development of male sexual characteristics. As a result, her external genitalia and overall appearance were typically female, despite having a male chromosomal profile.

Why do these variations occur?

Biological sex does not depend solely on external genitalia. It involves several levels:

• Chromosomes (XX, XY, or other variations)

• Gonads (ovaries or testes)

• Sex hormones (testosterone, estrogen)

• Body’s sensitivity to these hormones

• External appearance at birth

A difference at any one of these levels can create a variation in sexual development.

Main Variations in Sexual Development (for everyone)

Androgen Insensitivity Syndrome (AIS)

• Chromosomes: XY

• Cause: The body is “insensitive” to testosterone

• Appearance: Female at birth (no uterus), breast development at puberty, but no menstruation

• Fertility: Pregnancy is not possible (absence of uterus)

👉 This was the case of my patient. This 17-year-old had grown up entirely as a girl. A simple gynecological malformation was suspected. But as a precaution, a genetic test was performed before surgery. The surprise: she had XY chromosomes. Her body, insensitive to testosterone, had never developed male organs. She was a woman in her lived experience, identity, and appearance—but genetically XY. Nature can be surprising, but never “wrong.”

Rokitansky Syndrome (MRKH)

• Chromosomes: XX

• Cause: Congenital absence of uterus and vagina

• Appearance: Female at birth, normal puberty, but no menstruation

• Fertility: Ovulation possible → pregnancy via IVF + surrogacy (where legal), but no spontaneous pregnancy

Gonadal Dysgenesis (Swyer Syndrome)

• Chromosomes: XY

• Cause: Gonads fail to develop → no sex hormone production

• Appearance: Female at birth, delayed or absent puberty without treatment

• Fertility: Uterus present → pregnancy possible via donor eggs

Congenital Adrenal Hyperplasia (CAH)

• Chromosomes: XX

• Cause: Excess “masculinizing” hormones during pregnancy

• Appearance: External genitalia may be “in-between” at birth

• Fertility: Often preserved

  
  

Chromosomal Mosaics (45,XO / 46,XY, etc.)

• Chromosomes: Mix in different cells

• Cause: Early anomaly after fertilization

• Appearance: Highly variable—fully female to mixed

• Fertility: Depends on proportion of functional cells

Could it happen without knowing?

In most cases, these variations are detected in childhood or puberty.However, some cases—like my XY patient who lived her life as a girl—only become evident in adolescence or adulthood, often due to:

• absent menstruation

• infertility

• or accidental discovery during an exam

These situations are rare but real—and they show that biological sex is much more complex than “XX = female / XY = male.”

When to consult a doctor

• Absence of menstruation by age 15–16

• Difficulty conceiving

• Ambiguous genitalia at birth

• Known family history

A simple consultation, ultrasound, and—if necessary—a genetic test can clarify the situation.

Final Summary

Yes, it is possible—though rare—for someone to live their life as a woman and discover through medical testing that they are genetically male. Intersex traits, chromosomal variations, and hormonal differences reveal that human biology is complex, rich, and sometimes surprising.

These variations remind us that every body is unique and precious.Respect your body, your story, and those of others, and never hesitate to seek medical advice if you have questions or concerns.

Warm regards,

Dr. Sandra Yene Amougui