Is DNA Direct or Indirect Evidence?

 
 
 



18 March 2014

Ralph and Robert are strangers. They have just "met" through a DNA testing company that reports they have identical mitachondrial DNA. Would you say that they have direct evidence of a kinship or indirect evidence?

(For citation models treating various types of genetic testing reports, see EE 4.27.)

EE
EE's picture
TUESDAY'S TEST: EE's Answer

As we suspected, this is a question for which few dare to venture a public opinion! While most brave souls who have messaged us privately have split hairs nicely, several (and one Facebook commenter) has offered a common belief that deserves addressing.

Whether something is evidence of any type depends upon what the question is. With this in mind, many researchers will consider a piece of information to be indirect evidence if it does not provide a complete answer to some burning research issue. However, the distinction between direct and indirect is not  one of completeness. (Any researcher who hopes for a record that provides a complete answer to an issue is likely to never find it!)  Direct evidence need not be complete or even accurate. It's direct evidence simply because it directly addresses our research question to one extent or another. It's then up to us to put that evidence in context of our other findings to determine the answer.

In today's "Test," the evidence does directly answer the question as to whether Ralph and Robert have "evidence of kinship." If the question were rephrased to ask, "How are Ralph and Robert related," then we would still have direct evidence that they were related in some way through each of their mother's mother's mothers, etc. We would not have a complete or specific answer—and it could take months or years of documentary research to assemble that answer—but the DNA evidence still directly addresses the question of a genetic kinship and provides part of the answer: it tells them that they are kin through a mitochondrial line.

If you’d like a “refresher” on the subject of direct vs. indirect evidence, you’ll find one at https://www.evidenceexplained.com/content/quicklesson-17-evidence-analysis-process-map.

The Editor