Colleague of Alfred Kinsey who helped him conduct his influential sex research and co-authored with him his landmark books: Sexual Behavior in the Human Male in 1948 and Sexual Behavior in the Human Female in 1953.
A clinical psychologist by training, he conducted nearly half of the 18,000 interviews that formed the basis of Kinsey's two-volume work 'Sexual Behavior in the Human Male' and 'Sexual Behavior in the Human Female.'
After Kinsey's death, he published a biography of the doctor that attributed his success in research to his ability to get people to open up.
He had two sons and a daughter with his wife of 64 years, Martha Sindling.
Chris O'Donnell portrayed him in the 2004 biopic, Kinsey.