America has more than its share of eccentric art patrons — one thinks of Henry Frick, that scourge of union organizers, or Albert Barnes, who took malicious pleasure in barring art historians from his cloistered collection — but nothing quite like the querulous Clark brothers. Stephen and Sterling Clark absorbed from their dilettantish father a taste for fine art and, as heirs to the mighty Singer sewing machine company, the means to indulge it. Yet their aesthetic and personal styles could not have been more different, and their paths increasingly diverged, culminating in 1923 with a bloody fistfight in the family boardroom that ended all contact.

Such is the subject of Nicholas Fox Weber’s fine new study, “The Clarks of Cooperstown” (Knopf, 420 pages, $35), an unusually rewarding family portrait. It begins in 1849 when Edward Clark, the subjects’ grandfather, formed a partnership with Isaac Merritt Singer, the founder of the Singer company. A charming rogue who dabbled in acting and inventing, Singer was careless in both his personal life (he fathered at least 20 children by a succession of wives and mistresses) and his work. To put together his efficient and affordable sewing machine, he blithely cribbed from the patented inventions of others. To handle the ensuing lawsuits, Singer turned to Edward Clark, a staid and courtly New York lawyer who had a knack for knowing precisely what sort of cash settlement would satisfy a litigant. In exchange he received a three-eighth share of the business, although Mrs. Clark refused to allow the scandalous Singer into her house. The conflict between the free-spirited Sterling and the abstemious Stephen (described as morticianlike in demeanor) reprised the relationship between Singer and Clark.

The most intriguing personality here, however, is Alfred Corning Clark (1844–96), Edward’s son. Bored by the affairs of the Singer company, Alfred went to Europe to study the piano and art, and later became the music critic for the New York Times. Although he married and fathered four sons, his heart did not seem to have been in the marriage. Mr. Weber shows how Alfred spent as much time as possible in Paris, lavishing his attention and money on young men, including a Norwegian singer and later a young American sculptor named George Grey Barnard.

His patronage entailed gifts of the most extravagant sort. He offered $50,000 to the father of Josef Hofmann, the 11-year-old piano prodigy, if the boy would cease performing until he was 18, using the time to study (his training with Anton Rubinstein would make him one of the world’s great pianists). In these impulsive gestures, philanthropic and erotic motivations evidently mingled, though Mr. Weber is appropriately reticent to speculate about what we cannot know. At any rate, Alfred’s sons grew up in an atmosphere of lavish spending in the cause of art but also — one must conclude — of a certain amount of sublimated family tension.

Of the two sons who became collectors, Sterling was the more flamboyant and picturesque figure. After studying engineering at Yale, he became something of an adventurer, fighting in the Spanish-American War and then the Boxer Rebellion, and later organizing and funding an expedition into northern China. Like his father, he risked becoming a mere dilettante, gamboling about in Paris where he studied Arabic and took boxing lessons. But after 1911, he began to buy art seriously, devoting ever more time and money to its acquisition. He was counseled by Barnard, his late father’s friend, who had a keen eye and knew the Paris art market. For his advice, Barnard received a 10% commission, which he promptly used to buy medieval sculpture. These purchases, indirect offshoots of Sterling’s art collecting, formed the heart of the Cloisters, the museum of medieval art that would rise on the site of Barnard’s studio.

During these earlier years of collecting, Sterling was joined by his younger brother. Stephen had also attended Yale but then became a lawyer, playing an active part in the running of the Singer company. In short order, their tastes developed along different lines. While both were drawn to French art of the 19th and early 20th century, Stephen had by far the more progressive taste, and he intelligently purchased major works by Cézanne and Seurat. But he was no snob, and he was among the first of his generation to appreciate such American modernists as Thomas Eakins and Alfred Pinkham Ryder. He would also become a major figure in the Museum of Modern Art, serving on the building committee that in 1939 produced America’s first modernist museum.

That sleek essay in the International Style could not be further removed from the taste of Sterling, who housed his collection in a marble classical temple in Williamstown, Mass., where it would form the Clark Art Institute. This too was a formidable collection, but one utterly lacking in early modernism. Where Stephen bought Cézanne, Sterling bought Renoir, and other artists of the most cloying sort (for those who do not like sentimental art, his gallery of Renoirs forms a kind of Impressionist chamber of horrors). And yet, having grown up with art, he was alert to quality and he acquired crucial works by Domenico Ghirlandaio and Piero della Francesca, at the time of his purchase, the only one in a private collection.

In the end, all personal taste — in art and otherwise — is an enigma, and one must be cautious in explaining it away as the legacy of family influence and childhood trauma. As the story of the Clarks shows, two brothers, brought up in the same aesthetic and moral universe, can take diametrically opposed paths. Mr. Weber is to be congratulated for telling this story with admirable restraint, and looking upon his subjects with kindness and sympathy, and without succumbing to melodrama. Would it be too much to ask him to turn his talents now to the imperious Dr. Barnes?

Mr. Lewis, a professor in the art department of Williams College, is the author, most recently, of “American Art and Architecture” (Thames and Hudson).