Transgender people have a different genetic makeup than non-transgender people. For transgender people, the genetic makeup of their sex chromosomes (the X and Y chromosomes that determine an individual's sex) is different from what is typically seen in non-transgender people.
Transgender people may have a different number of sex chromosomes than non-transgender people. For example, a transgender person may have two X chromosomes and one Y chromosome (XXY), or they may have one X chromosome and two Y chromosomes (XYY).
Transgender people may also have a different mix of sex hormones than non-transgender people. For example, a transgender person may have higher levels of testosterone than estradiol (a form of estrogen).
The differences in the genetic makeup of transgender people may account for some of the differences in their physical appearance and in their hormones. transgender people often have different shaped genitals than non-transgender people. transgender people may also have different sounding voices than non-transgender people.
The differences in the genetic makeup of transgender people may also account for some of the differences in their brain structure. transgender people often have a different ratio of gray matter to white matter in their brains than non-transgender people.