It doesn't have any of Jon's DNA at least not according to the seller.

The synthetic DNA they use to mark the vest is a gimmick by the authenticity company (all of those companies and thier certificates are scams, this is just a new scam twist), the idea is that they can chemically check the DNA marker on the collectible in question to be sure it is the same item they originally marked and not a counterfeit. The companies used to put holograms on thier certificates to convince people they were important authenticators instead of clever thieves, but these days they go to greter lengths of frippery.
Dave