Humans typically have 23 pairs of chromosomes, resulting in a total of 46 chromosomes. These chromosomes determine individual genetics traits as well as a person's gender.
Human chromosomes are typically distributed equally during reproduction, causing the children to be born with traits inherited from both the mother and father. Twenty two of the chromosome pairs are similar in both males and females, and a pair of X and Y chromosomes determine the sex. Humans born with both an X and Y chromosome are male, and those born with two X chromosomes are female. An imbalance in the number of sex chromosomes in an individual may lead to health issues such as mental retardation, growth impairment and infertility.