Prepared by Elisabeth Lindsay.
Recombination is a process in human reproduction that accounts for the differences and similarities in families and among cultures. In a simplified explanation, the DNA chromosomes of a mother and father are recombined or randomly mixed to create the DNA of an offspring, which is distinct in itself, yet bearing traits inherited from both the mother and father. Because the process of recombination creates a random mix of DNA, the DNA of each offspring is different -- like stirring a soup, not everyone served gets the exact same mix of ingredients. Further, the offspring of each generation receive DNA from their parents that underwent recombination from their parents before them, and so on through the generations. Those who are closely related have fewer differences in their DNA than those who are more distantly related, and yet, the same DNA genes or markers may be found in the DNA of distantly related individuals.
In DNA studies used for genealogy, a number of markers are compared across a stand of DNA to determine whether or not two individuals may be related, and how recently they may share a common ancestor. For more information on DNA studies and their uses in genealogy, see the GenWeekly articles Beyond the Paper Trail: Discovering Family History with Different DNA Tests ($) and SNPs and Snails: What is your deep ancestry? ($)