Derivative records

Inquiring minds have asked, “About DNA and the GPS: How is DNA related as to source, information, and evidence with regard to the match and the most recent common ancestor?"

Yesterday, we tackled the first issue: separating two different tools that are often mentally merged:

Oh, how we love records that are neatly typed and nicely indexed. Sure, we've heard all those admonitions about consulting original records rather than derivatives. But let's get real. When somebody lived in thirteen different counties in 5 different states, that's a lot of records to plow through. When the records have been "processed" and published, we're going to use those published versions, right?