Sex chromosomes are the chromosomes within a cell that determine the sex of an organism. In all organism cells, with the exception of the sperm and eggs and the gametophyte generation in plants, chromosomes are arranged in pairs called homologous pairs. Each chromosome in the homologous pair comes from a different parent. A cell that has both chromosomes of each homologous pair is a diploid cell. In the human body, diploid cells have 46 chromosomes arranged in 23 homologous pairs.

In humans, each diploid cell has two sex chromosomes that make up one of the 23 homologous pairs of chromosomes. However, unlike all of the other homologous pairs, the sex chromosomes are not always the same size and therefore do not always have genes for all of the same traits.

There are two types of sex chromosomes, the X chromosome and the Y chromosome. The X chromosome is larger...