X Chromosome DNA
The X chromosome is one of the chromosomes that determines gender. Females have two X chromosomes. Males have one X and one Y chromosome. In a Mother, the X chromosomes behave just like autosomes. Her X chromosomes go through recombination, then she passes one along to each child, regardless of whether the child is male or female.
A father passes a copy of his X chromosome to his daughters, but not to his sons. Since he has only one X chromosome, it does not go through recombination. Because of its unique inheritance pattern, X chromosome DNA contains genetic information from some but not all of a person’s ancestors. X chromosome DNA becomes more fragmented through the generations, although not as quickly as autosomal DNA. Like autosomal DNA, it is more informative about our more recent ancestry.
