fmjones2

In a chromosome (i.e. 2 chromatids), is it correct that there are 2 separate (and identical) molecules of DNA? On Wikipedia, the definition of chromosome is stated as "a single piece of coiled DNA" (http://en.wikipedia.org/wiki/Chromosome), but I believe they mean a single chromatid is a single piece of coild DNA, correct?

Hi, I was wondering if someone could explain the genetics behind DNA genealogy tests. What are the actual genetic markers or fingerprints that allow companies like ancestry.com to define someone as Northern European, or Native American, or East Asian, etc. etc. Thank you