(CNBC) — More than 26 million people — more people than all of Australia — have shared their DNA with one of the four leading ancestry and health databases, allowing researchers to extrapolate data on virtually all Americans and raising some serious privacy concerns, according to the MIT Technology Review.

Consumers purchased the same number of at-home DNA tests in 2018 as in all of the previous years combined, according to the publication. If the trend continues, the companies could house the genetic information of over 100 million people — about a third of the U.S. population — within two years.

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