Question: Who were the main subjects modeled after in the famous "American Gothic" painting?
About the article "American Gothic", section "Abstract".

Candidate passages:
Wood's best known work is his 1930 painting "American Gothic", which is also one of the most famous paintings in American art, and one of the few images to reach the status of universally recognised cultural icon, comparable to Leonardo da Vinci's "Mona Lisa" and Edvard Munch's "The Scream".
It was first exhibited in 1930 at the Art Institute of Chicago, where it is still located.
It was given a $300 prize and made news stories country-wide, bringing Wood immediate recognition.
Since then, it has been borrowed and satirised endlessly for advertisements and cartoons.
Art critics who had favorable opinions about the painting, such as Gertrude Stein and Christopher Morley, assumed the painting was meant to be a satire of repression and narrow-mindedness of rural small-town life.
It was seen as part of the trend toward increasingly critical depictions of rural America, along the lines of Sherwood Anderson's "1919 Winesburg, Ohio", Sinclair Lewis' 1920 "Main Street", and Carl Van Vechten's "The Tattooed Countess" in literature.
Wood rejected this reading of it.
With the onset of the Great Depression, it came to be seen as a depiction of steadfast American pioneer spirit.
Another reading is that it is an ambiguous fusion of reverence and parody.
Wood's inspiration came from Eldon, southern Iowa, where a cottage designed in the Gothic Revival style with an upper window in the shape of a medieval pointed arch, provided the background and also the painting's title.
Wood decided to paint the house along with "the kind of people I fancied should live in that house."
The painting shows a farmer standing beside his spinster daughter, figures modeled by the artist's dentist and sister, Nan (1900–1990).
Wood's sister insisted that the painting depicts the farmer's daughter and not wife, disliking suggestions it was the farmer's wife, since that would mean that she looks older than Wood's sister preferred to think of herself.
The dentist, Dr. Byron McKeeby (1867–1950) was from Cedar Rapids, Iowa.
The woman is dressed in a dark print apron mimicking 19th century Americana with a cameo brooch and a tightly-knotted tie, and the couple are in the traditional roles of men and women, the man's pitchfork symbolizing hard labor.
The compositional severity and detailed technique derive from Northern Renaissance paintings, which Grant had looked at during three visits to Europe; after this he became increasingly aware of the Midwest's own legacy, which also informs the work.
It is a key image of Regionalism.
Wood was hired in 1940, along with eight other prominent American artists, to document and interpret dramatic scenes and characters during the production of the film "The Long Voyage Home", a cinematic adaptation of Eugene O'Neill's plays. 
Carpenter Gothic houses and small churches became common in North America in the late nineteenth century.
These structures adapted Gothic elements such as pointed arches, steep gables, and towers to traditional American light-frame construction.
The invention of the scroll saw and mass-produced wood moldings allowed a few of these structures to mimic the florid fenestration of the High Gothic.
But in most cases, Carpenter Gothic buildings were relatively unadorned, retaining only the basic elements of pointed-arch windows and steep gables.
Probably the best known example of Carpenter Gothic is the house in Eldon, Iowa, that Grant Wood used for the background of his famous painting American Gothic. 
Dearth's career can be divided into two periods.
Before 1912, he was a tonalism painter and is considered part of the American Barbizon school.
Spending most of his time in France, he was naturally fond of the picturesque country, and many of his subjects were found near Boulogne and Montreuil-sur-Mer.
These early works show a marked indifference to detail, a somewhat limited palette and a preference for a low key.
In art critic Charles Buchanan's words, Dearth was more or less repainting Barbizon, but was "inexpressively exquisite" and "a supreme gentleman of aethetics".
After 1912, he altered his technique and painted with broken colors, changing his subjects from the moody landscapes of Long Island and Montreuil to still life and figurative subjects in a style reminiscent of Adolphe Monticelli.
Such a style change was marked by his request to the Metropolitan Museum of Art in 1915 to replace his earlier work with his recent figure painting.
Although his late works include portraits and genre subject, his most numerous works of this period were paintings of rock pools in Brittany.
The canvases were highly colored; the pigment thickly applied with impressive decorative effect of the compositions.
In his final days, Dearth frequently used objects from his substantial collection of Gothic, Renaissance, and Eastern artifacts as his subjects or as backgrounds.
His final pictures incorporated important Japanese screens, early Chinese paintings, and stone carvings of the Wei period in still life arrangements or as backgrounds for some finely modeled figures. 
American Gothic is a painting by Grant Wood in the collection of the Art Institute of Chicago.
Wood's inspiration came from what is now known as the American Gothic House, and his decision to paint the house along with "the kind of people I fancied should live in that house."
The painting shows a farmer standing beside his spinster daughter.
The figures were modeled by the artist's sister and their dentist.
The woman is dressed in a colonial print apron evoking 19th-century Americana, and the couple are in the traditional roles of men and women, the man's pitchfork symbolizing hard labor, and the flowers over the woman's right shoulder suggesting domesticity.
It is one of the most familiar images in 20th-century American art, and has been widely parodied in American popular culture.
The American Gothic House, also known as the Dibble House, is a house in Eldon, Iowa, designed in the Gothic Revival style with a distinctive upper window.
It was the backdrop of the 1930 painting "American Gothic" by Grant Wood.
Generally considered Wood's most famous work and among the most recognized paintings in twentieth century American art, the painting is the model for hundreds of parodies across every creative medium.
Grant Wood, who observed the house only once in his lifetime, made only an initial sketch of the house—he completed "American Gothic" at his studio in Cedar Rapids.
First owned by Eldon resident Charles Dibble after its construction in 1881 and 1882, the home was (with one 1897 exception) a private residence until the late twentieth century.
After a thirty-year preservation effort culminated with the donation of the house in 1991 to the State Historical Society of Iowa, the site now includes the original house in its 1930 form and a visitors center.
The house was listed on the National Register of Historic Places in 1974.
Since 1991, various caretakers have continued to rent the home privately.