Industry giants Ancestry.com, 23andMe, MyHeritage and FamilyTreeDNA market their services online, share test results on websites, and even offer tutorials on how to search for relatives in phone directories, or share results in social media. They often also claim rights to your genetic data and sell access to their databases to big pharmaceutical and medtech companies.

In terms of internet health, it’s part of a worrying trend of corporations to acquire personal data about people and act in their own best interests, not yours. OK, so test results can also lead to important discoveries about your personal health, and can also be shared for non-profit biomedical research in the public interest. But before you give in to your curiosity, here are 23 reasons not to reveal your DNA – one for each pair of the chromosomes in a human cell.

Further reading How DNA Testing Botched My Family’s Heritage, and Probably Yours, Too, Gizmodo, 2018

Ancestry wants your spit, your DNA and your trust. Should you give them all three?, McClatchy, 2018

The Forensic Genetics Policy Initiative – Country Wiki

If you still decide to submit your DNA for testing, the U.S. Federal Trade Commission offers sound advice to consumers: compare privacy policies before you pick a company, choose your account options carefully, recognize the risks, and report any concerns to authorities. To counteract the dominance of commercial companies, you can also contribute your data to non-profit research repositories like All of Us or DNA.Land that are open to public scrutiny.

If you regret a choice you made in the past, you could have your DNA data deleted and request that your sample be destroyed. Consumer DNA testing is an example of why strong data protection laws are so important. In Europe, the General Data Protection Regulation (GDPR) offers some protections, but elsewhere you have few rights when you hand over sensitive data.