It’s tempting to begin as Dr. Kinsey would himself, by putting him in the appropriate category.

Pioneering sex researcher Alfred Kinsey was not a physician or an anthropologist, the disciplines that would seem most likely for the study of human sexuality. He was an entomologist and zoologist who devoted the first 20 years of his career to the study of gall wing wasps. He collected and examined over six million specimens.

Kinsey was, above all, a taxonomist, specializing in the “classification of organisms in an ordered system that indicates natural relationships.” And that turned out to be the ideal background for creating the first institute for the study of sexual behavior.

Writer/director Bill Condon and star Liam Neeson brilliantly show us how Kinsey’s passion for categorization and information transcended the distractions of morality or squeamishness.

We first see Kinsey developing the interview method that would lead thousands of people to confide their deepest secrets to him and his researchers, and then we see him as a child, listening to his father (John Ligthgow) preach hellfire and damnation. This is where Kinsey locates the twin roots of his life’s work — it will not only be a reaction to his father’s obsessive revulsion about sex but also a continuation of his father’s own taxonomic sensibility. Kinsey senior lists all of the occasions and inspirations for sin as painstakingly as years later his son will gently but persistently inquire in thousands of interviews about his subjects experiences with every possible form of sexual connection and exploration.

As usually happens, the greatest strength of Kinsey’s approach, his non-judgmental passion for data, was his greatest weakness as well. He says that love is the answer, while sex poses the questions, but he finds out that, as much as he — ever the taxonomist — would like to make a distinction between fact, morality, and emotion, sex has a messy way of overlapping into all of them. As he explores his own sexuality, as much out of that same impulse for information as out of a search for passion or intimacy, he is unwilling to acknowledge how much emotional damage it causes, even to himself.

Even in the pursuit of pure science, he cannot help creating ethical dilemmas. Kinsey’s researchers engage in experiments in both the technical and more casual sense of the term — literally participating in some of the sexual encounters filmed by the team and also becoming involved with each other’s spouses as a consequence of constant and norm-free study of sexuality. Finally, there is a moment when a subject is so loathsome that one of the researchers excuses himself; he cannot listen to the monster whose very act of describing his predatory encounters seems to be providing him with sexual satisfaction. But Kinsey continues. What matters to him is the data; if others can seek cures or set policy, the data must be there as a foundation.

Kinsey even involves his family. Typical dinnertime conversation includes the frankest discussion of sexual matters. And in a beautifully conceived scene, Kinsey interviews his own father, an incomplete encounter that is nonetheless far more revealing than any other they have ever had.

The cast is superb, especially Linney, Sarsgaard, and Neeson. Neeson brilliantly conveys Kinsey’s scientific curiousity and the single-mindedness that is both admirable and infuriating. In a brief cameo near the end, Lynn Redgrave makes a moving statement that is a perfect capstone to the story.

Parents should know that this movie has very graphic and explicit sexual references and situations, including clinical and informal discussions and depictions of a wide range of sexual experiences and activities, including adultery and homosexuality. Characters use extremely strong language including clinical and slang terms for sexual acts. Characters drink and smoke. The movie includes some tense emotional scenes and some minor scuffling. A strength of the movie is its depiction of early concerns about equal treatment for women and minorities, including gays and lesbians.

Families who see this movie should talk about why Kinsey’s work created such an uproar. How do we know — how do we decide — what “normal” means? Could anyone be as controversial today as Kinsey was in the 1950′s? Why does Mac laugh after meeting Kinsey’s parents? What does that tell you about her? What made it possible for Kinsey to be a different kind of father to his children than his father was to him? What did Kinsey learn from his interview with his father? Why were Kinsey and his staff so wrong about the impact that their sexual experimentation would have on their wives?

Families who appreciate this movie will also enjoy A Beautiful Mind, with Russell Crowe as mathematician John Nash, who struggled with mental illness. They might also like to take a look at an odd artifact inspired by Dr. Kinsey’s work, The Chapman Report, a lurid fictional portrayal of women who are interviewed for a Kinsey-style research project. Some might want to read one of the biographies: Alfred C. Kinsey : A Public/Private Life by James H. Jones or Sex the Measure of All Things: A Life of Alfred C. Kinsey by Jonathan Gathorne-Hardy, which was used as the basis for the screenplay.