Feel like the right gender in the wrong body? The answer to gender dysphoria may be in your brain’s BSTc.

If you feel like you’re the right gender in the wrong body, your brain is likely telling you that your true identity, based on brain structure and function, doesn’t match the way your body developed. This is known as gender dysphoria, commonly discussed as transgender.

Don’t worry about unfamiliar terms concerning structures within the brain – just be aware that there are parts of the brain believed to determine a person’s sense of gender identity. Following the brief list of structures, differences that occur within them, and how these differences were identified, the explanation gets simpler, with more familiar terminology. You may also want to browse through the Home and About pages.

While research is ongoing, as of April 2021 certain structures in and near the brain’s hypothalamus have been associated with gender identity:

• central nucleus of the bed nucleus of the stria terminalis (BSTc)
• interstitial nucleus of the anterior hypothalamus-3 (INAH-3)
• infundibulum nucleus

The BSTc in men is about 40% larger and has nearly twice as many somatostatin neurons as in women. This structure, near the brain’s hypothalamus, has been associated with gender identity but not with sexual orientation.

Postmortem studies of donated brain tissue have shown that genetically male male-to-female transsexuals have been found to possess a female-patterned BSTc (Swaab, 1995). The single genetically female female-to-male subject available did, indeed, possess a male-patterned BSTc. (Reports indicate that genetically male, male-to-female transsexuals occur at the rate of one in 10,000 individuals, whereas genetically female, female-to-male transsexuals are one in 30,000.)

Ivanka Savic’s 2008 functional brain-scan studies of pre-operative male-to-female transsexuals who had not yet undergone hormone therapy support Dr. Swaab’s 1995 findings.

The INAH-3, located in the brain’s hypothalamus, has been associated with both gender identity and sexual orientation.

How does this brain-body incongruity occur? Sexual anatomy develops during the first half of fetal development, while certain male-female differentiated brain structures develop during the second half of fetal development.

If a fetus is exposed to changes in sex hormones, drugs taken by the mother, or environmental chemicals or toxins during formation of sexually-differentiated brain structures, these brain structures may be pushed away from the patterning set in the sex organs and genitals during the first half of fetal development, and toward patterning of the other sex.

Timing of hormonal and chemical exposures are critical, since various brain structures as well as anatomy develop at different times. It’s not simply that anatomical development may not agree with brain patterning. Internal sex organs and external genitals may be incongruent with one another. Brain structures that set sexual orientation may be inconsistent with brain structures that set gender identity.

If a genetic male (possesses a Y chromosome) or genetic female (has at least one X and no Y chromosome) develops both internal and external sexual organs consistent with their genetics during the first half of fetal development, and then during the second half of fetal development is subject to influences that push development of one or more brain structures associated with gender identity in a different direction, this can account for an individual feeling like they were born into the wrong body.

Additionally, timing and possible fluctuations in hormonal or chemical exposures may determine whether an individual:

• feels attracted to the opposite sex
• feels attracted to the same sex
• feels sexually attracted to both men and women
• does not feel sexually attracted to anyone

The main page of this site contains additional information on some of the factors that enter into the mosaic that can occur during sexual development and identity of the fetus.

It should be noted that exposure to sex hormones after birth will not change the structure of the brain or one’s sexual orientation or gender identity. Hormone therapy may, however, help to bring an individual’s body in line with the dictates of their brain’s gender identity.

Body Mapping

In 2007, V. S. Ramachandran proposed a link between transsexuality and body mapping, or Body Integrity Identity Disorder (BIID), in which a person feels strongly that a part of their body doesn’t belong. Body mapping occurs in the brain during early fetal development. Though this connection between BIID and transsexuality has not been proved, it’s interesting to note that 19% of BIID patients also have gender identity issues, and 38% are bisexual or homosexual.

For Further Information…

Additional information on the mosaic complexities and possible inconsistent mix of female and male development in both anatomical and brain development can be found in Not a Choice: What you weren’t taught about the biology of sex and gender.

Sign up below for a free download of a pdf file containing articles and information from this site titled, Why LGBTQI? It’s set in the brain. It is not a choice.

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