beginner's question

[LindaLord]

I am new to all of this so this may be a very basic question.? ? The web pages seem to say that the DNA test can tell us (my first cousin and me) if we share a common ancestor with some other guy. Here is the question: Unless the test facility has access to DNA from some of those long dead Lords buried in Connecticut, I don't know how they can compare us.

Thanks
Linda