One concern to get out of the way up front is how the sample is acquired. Be sure to explain that the test is done using saliva or a cheek swab (depending on the testing company), and not by blood. People who have never considered a test may assume it involves needles and blood.
Vague Privacy Concerns
Some people will feel that taking a test means that "the government will get their DNA". But, they are usually not able to say exactly why the government would want their DNA, or why that would be bad. Nothing you can say will assuage the real tin-foil-hat types, but here are some reasons not to be so concerned.
- The Government already has your name, address, date of birth, place of birth, SSN and how much money you made last year. What would knowing your DNA information actually do for them? If anything, DNA is simply a type of identification, like fingerprints.
- Your actual, physical, DNA sample never leaves the testing company. They store it in a freezer.
- Even the testing company doesn't know your entire DNA sequence. That is too expensive at present (2020). They only determine a partial sequence.
- Your detailed DNA base pair data never leaves the testing company unless you download it. (Many people do that to transfer their result to another company.)
The most common and realistic risks occur in the normal, intended use of the DNA test: matching relatives and estimating your ethnicity. These risks are primarily of the family discovery and drama type, where family secrets are exposed:
- You may find that your parents or grandparents are not who you expected. This can be more or less traumatic depending on your family situation. This is often evidence of marital infidelity or rape and can cause a family crisis.
- Your test may not show the ethnicity you are expecting. Many people's personal identity is closely tied to their ethnicity, and finding a different ethnicity can cause identity issues. You may also find that you have cousins who are of a different race or ethnicity, and have trouble accepting that.
- You may discover the existence of close family members such as half-siblings, aunts, uncles and cousins and even children that were previously unknown. This is often evidence of marital infidelity or rape and can cause a family crisis.
Some of these risks can also become benefits. Many people develop a close relationship with new-found family and are ultimately thrilled to have found them.
There is one rather boring risk:
- Your DNA test may tell you nothing you didn't already know, or you may have very few or very distant matches, therefore you may feel you wasted your money. For Y-DNA tests, especially, it is possible to have zero matches. This is partially compensated for by the fact that as more people take the test(s), more matches will appear over time.
DNA Use by Law Enforcement
DNA can be used to identify suspects in crime by comparing evidence left at crime scenes with DNA from known individuals. If you or your close family lead a life of crime, or otherwise leave your DNA at crime scenes, you probably shouldn't take a DNA test. Similarly if you or your close family are engaged in espionage or other clandestine activities, you may not want to take a DNA test.
Recently forensic genetic genealogy has been able to identify suspects by comparing their DNA to the test results of, say, 2nd or 3rd cousins, who have taken a DNA test. This has mostly happened via GEDMatch, which is a site where people have voluntarily posted their DNA results for genealogy purposes. GEDMatch now allows law enforcement access only on an opt-in basis. Other testing sites do not allow routine law enforcement access at all, but may have to respond to a subpoena.
Genetic genealogy is, at present, only being applied to rape and murder cases or to unidentified crime victims. The following can be considered benefits or risks, depending on your viewpoint.
- Your DNA test might be used by law enforcement to help identify one of your relatives as the perpetrator of a crime.
- Your DNA test might be used by law enforcement to help identify a John Doe/Jane Doe corpse as one of your relatives.