Today I was asked a question from someone who is trying to prove a relationship within his family: "How can DNA tell me I'm related to someone if that person is dead and was never tested?" That's really a great question, and here is a relatively short answer: We inherit all of our DNA from our parents. First, there is autosomal DNA (atDNA), which makes up our 46 chromosomes. This is what AncestryDNA and 23andMe test specifically; the third largest company, FamilyTreeDNA, te