The Pentagon has issued a directive advising military members to beware of the growing popularity of the home DNA and ancestry kits, as they pose a higher security risk for military members than for their civilian counterparts.

The home kits are growing in popularity and are at this time of year a popular Christmas gift so that people can trace their ancestry. So far, in a study conducted by the Massachusetts Institue of Technology (MIT), over 26 million people have voluntarily sent their DNA to be tested. That number is expected to skyrocket to over 100 million by 2021.

That’s what worries some Pentagon officials. Under Secretary of Defense for Intelligence Joseph Kernan and acting Under Secretary of Defense for Personnel and Readiness James Stewart, said in a memorandum dated December 20, that DNA testing companies were targeting military members with discounts and other undisclosed incentives.

“These genetic tests are largely unregulated and could expose personal and genetic information, and potentially create unintended security consequences and increased risk to the joint force and mission,” the memorandum read. “Tests that provide health information have varying levels of validity, and many are not reviewed by the Food and Drug Administration before they are offered.”