The grandson of former US President Warren G Harding has launched a legal bid to have the Republican’s remains exhumed to confirm they are related.
James Blaesing told a court he wants to establish his ancestry with “scientific certainty”.
But other members of Harding’s family have opposed the request, filed in May.
They say they have accepted DNA evidence that Mr Blaesing’s mother, Elizabeth Ann Blaesing, was the daughter of Harding and Nan Britton.
Harding, the 29th president of the US, had an extramarital affair with Britton before and during his presidency, between 1921 and 1923.
The affair only came to light after Harding died of a heart attack while still in office in 1923.
Britton revealed their relationship in a 1927 book, The President’s Daughter, but never sought DNA evidence confirming Harding’s paternity of the child. Harding had no other children.
Then in 2015, genetic testing confirmed a match between Mr Blaesing’s DNA and that of two Harding descendants. Mr Blaesing’s biological link to Harding was officially declared by AncestryDNA, a division of Ancestry.com.
Despite this, grievances have surfaced ahead of the 100-year anniversary of Harding’s 1920 election as president.
Harding’s benefactors are preparing to mark the occasion with site upgrades and a new presidential centre in Marion, the Ohio city near which he was born in 1865.
But Mr Blaesing said he and his mother have not received the recognition they deserve in the new museum.
“I did the test and we brought it to the public in 2015. It’s now 2020 and no one has asked me one thing,” he said.
Mr Blaesing said he deserves to “have his story, his mother’s story and his grandmother’s story included within the hallowed halls and museums in this town”.
He said he hoped to change that by providing further DNA evidence of his biological link to Harding.
Mr Blaesing’s lawsuit to exhume Harding’s remains from his presidential memorial in Marion has been challenged by another branch of the family.
“Sadly, widespread, public recognition and acceptance by the descendants, historians and biographers (and Mr Blaesing himself) that Mr Blaesing is President Harding’s grandson is not enough for him,” relatives said in a court filing.
Ohio History Connection, which manages the Harding home and memorial, told the Associated Press news agency that it takes no position on the family dispute.
It did, however, tell the court to consider a host of issues before disrupting the Harding Memorial’s sealed sarcophagus.
The non-profit organisation said it accepted the 2015 DNA results “as fact” and was planning to include a section of the new museum on Britton and her daughter.