Gender dysphoria - Causes 

The exact cause of gender dysphoria is unknown and there is much debate over the condition’s possible causes. 

Gender dysphoria was traditionally thought to be a purely psychiatric condition, which meant that its causes were believed to originate in the mind. However, recent studies have challenged this and suggested that gender dysphoria may have biological causes associated with the development of gender identity before birth.

More research is needed before the causes of gender dysphoria can be fully understood, but it is widely agreed that it cannot be thought of as a purely psychiatric condition.

Typical gender development

Much of the crucial gender development that determines your gender identity happens in the womb (uterus). To understand how gender identity can be affected by development in the womb, it is necessary to know how it normally works.

Your sex is determined by chromosomes. Chromosomes are the parts of a cell that contain genes (units of genetic material that determine your characteristics). You have two sex chromosomes: one from your mother and one from your father.

During early pregnancy, all unborn babies are female because only the female sex chromosome (the X chromosome) that is inherited from the mother is active. At the eighth week of gestation, the sex chromosome that is inherited from the father becomes active, which can be either an X chromosome (female) or a Y chromosome (male).

If the sex chromosome that is inherited from the father is X, the unborn baby (foetus) will continue to develop as female with a surge of female hormones. The female hormones work in harmony on the brain, gonads (sex organs), genitals and reproductive organs, so that the sex and gender are both female.

If the sex chromosome that is inherited from the father is Y, the foetus will go on to develop as male. The Y chromosome causes a surge of testosterone and other male hormones, which initiates the development of male characteristics, such as testes. The testosterone and other hormones work in harmony on the brain, gonads (sex organs) and genitals, so that the sex and gender are both male.

Therefore, in most cases, a female baby has XX chromosomes and a male baby has XY chromosomes.

Changes to gender development

Gender development is complex and there are many possible variations that can cause confusion between a person’s sex, gender identity and gender role. Some examples of the possible variations are outlined below. However, it is important to remember that these are not yet fully understood. 

Malfunctioning hormones

In rare cases, the hormones that trigger the development of sex and gender may not work properly on the brain, gonads and genitals, causing variations between them. For example, the sex (as determined physically by the gonads and genitals) could be male, while the gender (as determined by the brain) could be female.

This could be caused by additional hormones in the mother’s system or by the foetus’s insensitivity to the hormones, known as androgen insensitivity syndrome (AIS). In this way, gender dysphoria may be caused by hormones not working properly within the womb.

See the Health A-Z topic about Androgen insensitivity syndrome for more information about this condition.

Other rare conditions

Other rare conditions, such as congenital adrenal hyperplasia (CAH), and intersex conditions (also known as hermaphroditism) may also result in gender dysphoria.

In CAH, a female foetus’s adrenal glands (two small, triangular-shaped glands located above the kidneys) cause a high level of male hormones to be produced. This enlarges the female genitals. In some cases, they may be so enlarged that the baby is thought to be male when she is born.

Intersex conditions cause babies to be born with the genitalia of both sexes (or ambiguous genitalia). In such cases, it was recommended that the child’s parents should choose which gender to bring up their child. However, it is now thought to be better to wait until the child can choose their own gender identity before any surgery is carried out to confirm it.