J.P. Donleavy was born today in 1926. The Irish American novelist was born in New York and now lives in Westmeath. His portrayal of the adulterous, bed-hopping exploits of a student in post-war Dublin earned him fame and notoriety in equal measure when his debut novel "The Ginger Man" was published in 1955.

But while he has happily courted controversy through the sexually charged pages of his books, an extraordinary story of infidelity in his own life has remained a closely guarded secret for more than 30 years.

Neither of the children born during his second marriage, to the actress Mary Wilson Price, was fathered by him.

She had affairs with Kieran Guinness and his brother Finn, scions of the brewing dynasty, and had a child by each of them while she was still married to Donleavy. Kieran Guinness, 62, is the father of Rebecca, 32, while Finn Guinness, 66, is the father of Rory 30.

Although the novelist, who lives on an 180-acre estate outside Mullingar, Co. Westmeath, has known for more than 20 years that he is not their father, he has never admitted it publicly and lists them in his entry in Who’s Who.

Kieran Guinness, who breeds racehorses in Ireland, said he remains a close friend of Donleavy, but still, has no idea when the author first discovered the truth.

Guinness met the former Mrs. Donleavy when he was the master of the local hunt in the 1970s.

Finn Guinness married Mary Wilson in 1989 after she split from Donleavy, and when they moved to England she and the two children took the Guinness name. The couple now run the Biddesden Stud in Wiltshire.

Donleavy, 85, also has two children with his first wife, Valerie Heron. They married in 1946 and were divorced in 1969. Donleavy and Mary Wilson Price married the following year.

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A family friend claimed that the paternity of both children was only established through DNA tests when Donleavy and Mary separated in 1988.

Despite their acrimonious divorce, the couple remains in contact.

Mary told Richard Kay of the Daily Mail, “I was in Ireland last week with Jane Birt (ex-wife of former BBC director general Lord Birt) and Jane Bland (wife of former BBC chairman Lord Bland) and we popped in for tea.

“There are matters involving our divorce and the children that I’m not prepared to talk about even now. I will say, though, that my ex-husband is a brilliant man.”

In a separate interview, Mary said, “All I will say is that my children are very, very, very lucky because they have the loveliest people involved in their lives in a paternal way -- Finn, Kieran, and JP -- who are loving and supportive to them equally.”

The Ginger Man has sold 45 million copies and has long been considered semi-biographical.

* Originally published in 2011.

‘Ginger Man’ author J.P. Donleavy.