FAMILY BUSINESS: During the six years David Nasaw spent researching and writing “The Patriach,” his new biography about Joseph P. Kennedy, he unearthed all sorts of details about the former ambassador. During an affair with Gloria Swanson, Kennedy splurged on a cottage for her and billed her for it. “He believed all’s fair in business. He thought if Gloria Swanson didn’t have the sense to get a good accountant — to hell with her,” Nasaw said during a Q&A at CUNY’s Graduate Center Monday night.

He also debunked such Kennedy trivia that the patriarch was a bootlegger and that he “bought the Pulitzer” for Jack Kennedy’s “Profiles in Courage” and that Ted Sorenson wrote it. Nasaw claims the then-aspiring president wrote the book with a team of editors and researchers (including Sorenson.) “But did he buy it? No…I mean Pulitzer committees make mistakes.”

In tune as the father of America’s most photographed Irish Catholic family was to how television would shape politics, he did not foot Jackie Kennedy’s shopping bills during the White House years. “He arranged that each kid had $1 million in a trust. Jackie didn’t need an extra allowance from Joseph P. Kennedy. Jack had more than enough money,” Nasaw said by phone Tuesday.

All Kennedy bills, however, were directed through the offices of Joseph P. Kennedy Enterprises where a team of accountants and tax people handle all the invoices. “Every bill — travel, hotels, you name it — went there,” Nasaw said. “I don’t know what bank account they were drawn from. But there was nothing out of the ordinary.”

What Nasaw could not add up was Rose Kennedy who seemed to accept her husband’s infidelities (with Clare Booth Luce among others) as part of marriage. When Joseph P. Kennedy did ask his wife to come with him on vacation, she replied, “No, I will just be in the way,” Nasaw said. Fortunately for the author, his friend Nancy Milford is knee-deep in a biography about the family’s matriarch. “Nancy and I spent a lot of time having lobster rolls in the Kennedy Library talking about her character,” Nasaw said.

And apparently, the Kennedy clan didn’t entirely understand how he has characterized Joseph Kennedy. In response to Christopher Buckley’s Nov. 18 review in The New York Times, Jean Kennedy Smith is said to be penning a letter to the editor of the Sunday Book Review on the family’s behalf.