The older Theroux criticises his younger brother's travel books for superficiality and says his novels are "beach reads''
His dislike is said to have simmered for the 14 years the Massachusetts- born brothers have shared the same profession and summer holidays in Cape Cod, but have studiously not spoken.
For, as the author of three obscure but high-brow novels, Alexander, 57, has long looked down on his younger, more successful brother, 55, who has spent much of his career in London.
This month, his irritation boiled over in a Massachusetts publication, Boston Magazine, in a review of Paul's make- believe memoir My Other Life, in which he described meeting the Queen at a dinner party.
Such is the review's nastiness that previous literary rivalries between siblings will henceforth pale into insignificance. Mr Theroux begins fairly quietly by trashing his brother's travel books.
"He angrily dismissed Af-ghanistan in a paragraph and Greece in a few sentences. He has ridiculed in print everyone from priests to high-school classmates, to Cape Codders to fat Samoans, to tasteless Americans to tubby Cantonese, to lazy Melanesians," observes Alexander.
"He has mocked famous poets and writers, R Lowell, R Frost, A Burgess, P Taylor, etc, and ... has found half the world wanting in goodness and grace, brains and bravery, cleanliness and character."
Having disposed of Paul's travel books, including The Great Railway Bazaar and The Pillars of Hercules, he moves on to Paul's novels, which are no more than "beach reads", Alexander suggests, only a step above Judith Krantz.
"He is ... smiled down on by the literary establishment, for the most part," Alexander continues. "Nobody I know has written so many books [20 novels, 10 travel books] with so little serious critical recognition to show for it.
Despite their differences, the Theroux brothers have had similar paths in many ways. Both are highly educated and have worked as academics while pursuing writing careers.
Paul moved to Britain in 1971, after marrying a producer for the BBC world service, and lived here for almost 20 years. When they separated, he left for Hawaii, where he married a Chinese-Hawaiian woman.
Fact and fiction intertwine in his books, which has caused him problems in the past, not least the time when he made up a story about meeting the Queen and Prince Philip at a private dinner party. Many believed his report that the Queen had talked about the "fuzzy wuzzy hair" of the prime minister of Papua New Guinea.
Alexander Theroux has taught at Harvard and Phillips Academy in Andover, Massachusetts. Thirteen years ago, perhaps his best-known novel, Darconville's Cat, was published, and he has also written short stories and essays.
The older Theroux believes that his brother's books have generated neither academic appreciation nor a cult following of loyal readers
This in itself may seem scarcely an indictment, but Mr Theroux has not finished. Paul "has bowel worries and eats prunes for breakfast", we learn. Further, he is a possession snob and a fussy traveller. Mr Theroux really plunges the stiletto, however, in his final comments: "Someone once said to me, uncharitably, `Paul is about Paul ... short, womanizing ... opinionated, and angry'," he writes.
And, finally, to the book he is reviewing which, unsurprisingly comes off little better. "It is a novel of contrition, pieced out by way of the contrivance of a writer at last taking a moment to satirise himself, not subtly ... and to come out - even if only for the space of a story - from the cruel, carious shadows which, like a crab, he has so long chosen to inhabit."
Readers of this literary suicide note may grasp why the Paul Theroux side of the family is understood to have perused the article with more hilarity than horror.Reuse content