Both “sex” and “gender” are related to being a boy or a girl. “Sex” is about a person’s body parts and how their body grows and develops. A person’s sex is due to a mix of genetic factors and sex hormones. A person’s gender is about their sense of self.
Chromosomes are large groups of genes. You can think about genes as instruction codes that are packaged in a person’s chromosomes. There are some genes that are involved in sex development.
Most people have 46 chromosomes. Two of the chromosomes, the X and the Y, are called sex chromosomes. Most boys have one X and one Y chromosome. Most girls have two X chromosomes. However, some boys and girls may have different chromosome patterns. For example, some girls have one X and one Y chromosome.
Changes in some genes or chromosome patterns may explain why some people’s bodies develop differently.
Hormones are chemical messages that a person’s body makes. They tell the body how to grow and develop. Sex hormones make a person’s body parts develop in a male or female way, before birth and at puberty.
Sex hormones are made by glands inside the body called gonads. There are two types of gonads: testes and ovaries. Most boys have testes and most girls have ovaries. Genetic factors (for example, if a Y chromosome is present or not) are important for sex glands to develop into testes or ovaries.
Testes make hormones called androgens. Testosterone is one type of androgen. Ovaries make estrogen, and some testosterone. In addition, testes make sperm and ovaries make eggs.
Reproductive Body Parts
People have reproductive parts inside and outside their bodies. Gonads are one of the parts inside the body. Also inside the body, most girls have a vagina, a cervix and a uterus. The parts outside the body are called genitals. Most boys have a penis and a scrotum. Most girls have a clitoris, labia and a hole for the vagina.
Some people with DSD may have a mix of male and female reproductive parts or genitals that are not clearly male or female.