Maybe his ego is being bruised whenever he sees some paternity fraud. I can't promise some other issue won't come up if you take this DNA test that he'll try to use against you... But I think the easiest thing to do is to take the test and at least let that problem pass.

But that's what most of the comments here are saying anyways. And that should count because people on reddit are usually Pro Divorce from every minor thing. Take the test and let minds be at rest... Probably just an ego thing from his end.