(CNN) Whether this practice is beneficial or unethical depends on who you ask.

DNA tests are being performed on children and parents in an attempt to reunite migrant families separated at the US border, said a federal official with knowledge of the reunifications.

"The safety and security is paramount, and it is not uncommon for children to be trafficked or smuggled by those claiming to be parents," the official said.

"To our knowledge, this is a cheek swab and is being done to expedite parental verification and ensuring reunification with verified parents due to child welfare concerns."

The source could not discuss how long the practice has been taking place, if the testing requires consent or if the DNA is stored in a database.