What is definition of "blanket testing?"

there’s a topic in another section talking about “blanket DNA testing,” but i was curious as to what the definition of blanket testing is, can someone lay down some insight?

The thread title said “Blanket DNA Testing.” The meaning is DNA testing in all instances, or for all groups. Think of a blanket’s ability to cover an entire thing or group of things, which probably lead to a common metaphor and then to the definition of the word blanket.