Why the princes in the tower are staying six feet under

[ChazInAz]

9. Testing would be straightforward.

We already have two DNA samples from descendants of the boys' aunt that were used to identify Richard. Both skeletons in the urn still have most of their teeth. Obtaining material from them would be fairly simple.
Of course, we'll still never know who killed them. They may actually have died of natural causes, since the examination showed signs of dental abscesses. If so, that naturally leads one to wonder why Richard didn't mention their deaths.