Prepared by Elisabeth Lindsay.
Autosomal DNA is both simple and complex -- it is the story of life, the birds and the bees, and it begins in the human cell. Each human cell nucleus contains 46 DNA "packages" called chromosomes. Chromosomes come in matched pairs -- 22 pairs are autosomes, while the other pair, the X and Y chromosomes determine gender. Each pair of chromosomes are inherited through the generations in the same way. For each pair of autosomes, one comes from your mother and one from your father. Your parents autosomes came from their mother and father, and back through the generations, in a process known as recombination. Therefore, each of your autosomes is a mixture of those of your parents, your grandparents, great-grandparents and so on. Further, you and your full blood siblings have the same mix of autosomes, where half-siblings have only half of your autosomes, your mother or father, whichever the case may be. The closer the relative, the closer the autosomal match; however, because pieces of autosomal DNA are passed through the generations, near cousins and distant cousins may share pieces of the same autosomal DNA.
Autosomal DNA testing, which is available to both men and women, can provide information on recent and deep ancestry. Autosomal DNA testing is said to be effective for recent ancestry back five generations. It is also used to reveal a person's ethnic heritage in percentages; that is, what mix of ethnicities are represented in your DNA and to what degree. To learn more about DNA testing and its uses in genealogy, see the GenWeekly articles, Beyond the Paper Trail: Discovering Family History with Different DNA Tests and SNPs and Snails: What is your deep ancestry? ($).