The Pentagon has advised military members to avoid using take-home DNA kits because of concerns about “unintended security consequences and increased risk to the joint force and mission,” according to Yahoo News, which first reported on the internal memo. The memo doesn’t specifically lay out what the exact risks are, but it appears that it’s a generalized concern over health information affecting a military member’s ability to serve.

Sent on December 20th, the memo doesn’t specifically name any companies, but 23andMe and Ancestry.com both offer popular DNA testing kits meant to provide information about potential health risks and family information.

The New York Times confirmed the veracity of the memo with a Pentagon spokesperson who reiterated the concerns of the memo, though he wasn’t much more specific about what the concerns would be, saying “The unintentional discovery of markers that may affect readiness could affect a service member’s career.”

More specifically, the NYT notes, the US military is not required to ignore genetic information in the same way that civilian employers do thanks to the Genetic Information Nondiscrimination Act. That could mean that if a genetic test uncovered a risk factor for a certain disease, it could affect a military members’ future career.

Most consumer-facing DNA testing companies have pledged never to share DNA data with third parties without express customer consent. They made the pledge in 2018 after a public DNA database was used to identify the Golden State Killer, further promising to try to notify users if law enforcement demanded their information (though gag orders could theoretically prevent that).

The memo also expresses some worry over the anonymity and security of DNA data, stating such tests “could expose personal and genetic information.” While companies like 23andMe argue that they keep such data secure, it’s possible the Pentagon would rather not take the risk. If nothing else, it’s not like the Pentagon would be able to vet the security measures of every company offering DNA testing services. Fox Business reports that 23andMe says a “sample provider can ask for their sample to be destroyed. And the company has several layers of security that restrict customer information within the company.”

The NYT notes that the Pentagon isn’t suggesting military personnel avoid DNA testing entirely, however. It just recommends against home testing and a Pentagon spokesperson said that they should get their DNA tests “from a licensed professional.”