Professor Alfred Kinsey is being interviewed about his sexual history. Interspersed with the interview, are flashbacks from his childhood and young-adulthood. The young child years show his father, a lay minister, denouncing modern inventions as leading to sexual sin, then in early adolescence, humiliating him in a store by denouncing its keeper for showing him cigarettes, while his adolescence shows his experiences as a Boy Scout and a late teenage scene shows Kinsey disappointing his father by his chosen vocational intentions. It then shows adult Kinsey teaching at Indiana University as a professor of biology lecturing on gall wasps.
Kinsey falls in love with a student in his class, whom he calls Mac, and marries her. Consummation of their marriage is difficult at first, because of a medical problem Mac has that is fixed easily with minor surgery, after which it is shown that she has an equally intense sexual appetite as her husband. Meanwhile, at the University, Professor Kinsey, who is affectionately called "Prok" by his graduate students, meets with students after hours to offer individual sexual advice.
Later, in a fictional scene where his mother has just died and Alfred is back at his parents' home with grieving friends and relatives - including his sister, who is overweight and thus considered too unattractive to get a husband, and his brother, who is possibly an early boomerang generation man who moved back home after losing his business - Kinsey shocks his father by telling him his "big secret": that he's doing a sex survey and wants his father to contribute his own sexual history to it.
At a book party celebrating Kinsey's latest publication on gall wasps, Kinsey approaches the dean of students about an open-forum sex education course as opposed to the anti-sex propaganda taught in a general health class. Eventually, it is approved, but on the grounds that it is open only to teachers, graduate or senior students, and married students. Nevertheless, Kinsey begins, teaching the sex course to a packed auditorium.
Kinsey continues to answer students' questions in personal meetings but finds his answers to be severely limited by the complete paucity of scientific data about human sexual behavior. This leads Kinsey to pass out questionnaires in his sexual education class from which he learns of the enormous disparity between what society had assumed people do and what their actual practices are. After securing financial support from the Rockefeller Foundation, Kinsey and his research assistants, including his closest assistant, Clyde Martin, travel the country, interviewing subjects about their sexual histories.
As time progresses Kinsey begins realizing that sexuality within humans, including himself, is a lot more varied than was originally thought. The range of expression he creates later becomes known as the Kinsey scale, which ranks overall sexuality from completely heterosexual to completely homosexual and everything in-between.
The first sexological book Kinsey publishes, which is on the sexual habits of the male, is a large-scale success and a best seller. Kinsey's research turns to women, which is met with more controversy. With the release of the female volume, support for Kinsey declines. McCarthyist pressures lead the Rockefeller Foundation to withdraw its financial support, lest it be labeled "Communist" for backing the subversion of traditional American values.
Kinsey feels that he has failed everyone who has ever been a victim of sexual ignorance. A customs officer is tipped off to an importation of some of Kinsey's research material, which only exacerbates the financial situation of Kinsey's research organization. Kinsey suffers a heart attack, and is found to have developed an addiction to barbiturates. Meeting with other philanthropists fails to garner the support needed. Still, Kinsey continues his taking of sex histories.
The story returns to the initial interview with Kinsey, and he is asked about love and if he will ever attempt to conduct research on it. His response is that love is impossible to measure and impossible to quantify (and without measuring, he reminds us, there can be no science), but that it is important. The final scene is of Kinsey and his wife, pulling over to the side of the road for a nature walk. She remarks about a tree that has been there for a thousand years. Kinsey replies that the tree seems to display a strong love in the way its roots grip the earth. Afterwards, the two walk off together, Kinsey remarking "there's a lot of work to do".
Producer Gail Mutrux handed Bill Condon a biography of Kinsey in 1999 to spark his interest in writing a screenplay. Condon then based his original screenplay on elements in the biography combined with his own original research on Kinsey.
Ian McKellen was at one point in negotiations for a supporting role.
Kinsey was the first film permitted to show human genitalia uncensored in Japan, known for its strict censorship policies regarding genitalia.
The review aggregation website Rotten Tomatoes lists a rating of 90% positive based on reviews from 192 critics. On Metacritic, the film has a 79 out of 100 rating, indicating "generally favorable reviews".
The film grossed $10,254,979 domestically and $16,918,723 worldwide on an $11 million budget.
According to its IMDb profile, Kinsey
won 11 awards and received 27 other nominations.