Beginners Guide to DNA – This is a very understandable tutorial.
Update to Shared cM project link
Why it’s hard to figure out your MRCA: “The common ancestor between you and the person you match could share one of the surnames on your direct line of ancestors, but it is more likely to be among one of the descendants of your various fourth great-grandparents. For example, you have 64 fourth great- grandparents at the sixth generation level, and those you match will likely be connected to one of their descendants. It is very likely that you and your match will not recognize each other’s direct line surnames as there is a higher possibility that at some point a female in one or both of your lines married a surname that one of you does not recognize. For this reason, it is important to gather as much data on the descendants of those fourth great-grandparents as possible.”
Here’s the link to the article.
From DNA to Genetic Genealogy
Everything you wanted to know but were afraid to ask
Stephen P. Morse