Two of the chromosomes (the X and the Y chromosome) determine your sex as male or female when you are born. They are called sex chromosomes: Females have 2 X chromosomes. Males have 1 X and 1 Y chromosome.

Can you be a girl with a XY chromosome?

The X and Y chromosomes are called “sex chromosomes” because they contribute to how a person's sex develops. Most males have XY chromosomes and most women have XX chromosomes. But there are girls and women who have XY chromosomes. This can happen, for example, when a girl has androgen insensitivity syndrome.

What is the gender of YY?

Males with XYY syndrome have 47 chromosomes because of the extra Y chromosome. This condition is also sometimes called Jacob's syndrome, XYY karyotype, or YY syndrome. According to the National Institutes of Health, XYY syndrome occurs in 1 out of every 1,000 boys.