Could the brain offer cues to gender identity?

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Gender dysphoria, or the inability of an individual to mentally conform to the gender originally assigned at birth has been widely observed in children right from an early age. The knowledge about gender identity at such an early age has been widely debated to rely on biological factors that come into play much before puberty.

Genetics offers a plausible explanation, as identical twins are more likely than fraternal twins to both be trans.

However researchers are analyzing the brains of trans individuals to look for cues that could explain the preference to identify with the opposite gender than the one assigned at birth.

The fact that male and female brains are, on average, slightly different in structure, forms the basis of these studies.

Various studies have tried to look for specific signs in the brains of transgender people that could actually be more similar to the experienced gender. Magnetic resonance imaging or MRI was used to examine brains of 24 female-to-males and 18 male-to-females—both before and after treatment with cross-sex hormones by psychobiologist Antonio Guillamon of the National Distance Education University in Madrid and neuropsychologist Carme Junqué Plaja of the University of Barcelona.

Their results showed that the brain structures of transgenders were more similar to the experienced gender than the anatomical or natal gender even before the hormonal treatment.

For example, the female-to-male subjects had relatively thin subcortical areas (these areas tend to be thinner in men than in women). Male-to-female subjects tended to have thinner cortical regions in the right hemisphere, which is characteristic of a female brain. (Such differences became more pronounced after treatment.)

“Trans people have brains that are different from males and females, a unique kind of brain,” Guillamon explained. “It is simplistic to say that a female-to-male transgender person is a female trapped in a male body. It’s not because they have a male brain but a transsexual brain.”

In other studies, sex differences through brain functioning have been investigated. In one such study, psychologist Sarah M. Burke of VU University Medical Center in Amsterdam and biologist Julie Bakker of the Netherlands Institute for Neuroscience used functional MRI to examine 39 prepubertal and 41 adolescent boys and girls with gender dysphoria for their response to androstadienone, an odorous steroid with pheromone-like properties. The steroid causes different type of response in the hypothalamus of both men and women. They found that adolescent boys and girls with gender dysphoria had a response similar to their experienced gender. The results were less clear with the prepubertal children.

“This kind of study is important because sex differences in responding to odors cannot be influenced by training or environment.”says Baudewijntje Kreukels, an gender dysphoria expert at VU University Medical Center.

In another study that measured the reponses of boys and girls with gender dysphoria to echo-like sounds produced by the inner ear in response to a clicking noise, it was found that boys with gender dysphoria responded more like typical females. However, girls exhibiting gender dysphoria also responded like typical females.

In effect, these studies prove to a certain extent of the influence of biological characteristics in gender dysphoria. But considering the large variations that exist in the brains of men and women and also the large number of transgender people it would be hard to put a finger on the gender identity of a child with nothing but a series of tests.

Source: Scientificamerican