A request by a grandson of Warren G. Harding to prove his lineage with “scientific certainty” by exhuming his grandfather’s body has been denied by a judge in Ohio.

James Blaesing, whose grandmother, Nan Britton, wrote a tell-all book in 1928 about her affair with the 29th president, had already had the relationship established with help from Ancestry.com and DNA samples from two Harding descendants.

But one faction of the Harding family that was dismissive of Mr. Blaesing had cast doubt on the Ancestry genealogy, ostensibly because it was a relatively new, though reliable, method. So Mr. Blaesing sought to go further to establish direct proof that President Harding was his grandfather.

As the threat of an exhumation loomed, however, the resistant members of the family wrote letters to the court accepting the Ancestry results, said Dr. Peter Martin Harding, whose father is one of the former president’s nephews. Dr. Harding is one of the relatives who provided DNA to confirm Mr. Blaesing’s lineage.