Irving Gottesman set out to challenge the prevailing thinking in the 1960s that faulty parenting was mostly to blame for mental illnesses such as schizophrenia.

In studies of twins that brought him international renown, Gottesman showed the powerful role genes play. A father of two, he went on to publish 17 books and created the University of Minnesota's behavioral genetics program, the first in the country. He died of natural causes June 29 at 85.

Gottesman remained active on the U campus until his death, dispatching e-mails about the latest developments in psychology to a long list of colleagues.

Throughout his career, Gottesman remained focused on the everyday implications of scientific research. In 2000, he traveled to Hong Kong to testify in the legal case of several men blocked from civil service jobs because of a parent's mental illness. He remained hopeful that his research into schizophrenia would one day lead to a cure.

"The pioneering work that Irv did using the twin study method to tackle the nature vs. nurture issue really revolutionized our field," said Monica Luciana, the chair of the U's Department of Psychology.

Gottesman was born in Cleveland to Jewish immigrant parents from Hungary. He attended the Illinois Institute of Technology and after graduation served as a communications officer during the Korean War.

Gottesman earned his Ph.D. at the University of Minnesota, where he first became interested in comparing the personality traits of twins — an interest that diverged from the Freudian theory that dominated the field at the time. He started his career teaching at Harvard and the University of London.

In London, Gottesman undertook a study of twins hospitalized with diagnoses of schizophrenia. By comparing the incidence of the disease among identical twins, who share genetic profiles, and fraternal twins, he showed a genetic predisposition to the illness. Gottesman would go on to study imprisoned twins in Denmark in research that explored how genetics affect criminal behavior.

He returned to teach at the U in 1966, designing its behavioral genetics program soon after.

Matt McGue, a U psychology professor, took a class from Gottesman as a graduate student in the 1970s. McGue had recently completed his undergraduate studies at the University of California, Berkeley, where he had learned that flawed child-rearing causes schizophrenia and other mental illness.

"I heard a completely different story from Irv ­Gottesman," he said. "It was an eye-opening experience that changed my thinking about the nature of behavior."

In the earlier part of the century, the study of genetics had become co-opted by the eugenics movement, and Gottesman faced criticism for years. As a Jewish scientist who had lost relatives in the Holocaust, he took such criticism personally, said his wife, Carol, whom he married in 1970. He wrote about the abuses of genetic research in Nazi Germany.

Gottesman went on to teach at Washington University in St. Louis and the University of Virginia. He swept the major awards in his field, including the Hofheimer Prize for Research. He returned to the U in 2001 as professor emeritus after his retirement from teaching.

He published research papers annually and mentored junior faculty and graduate students. Colleagues like McGue, who codirects the U's Center for Twin and Family Research, received e-mails with links to articles and papers relevant to their research interests almost daily.

"What's really amazing about Irv is how incredibly involved he was with the profession right up until the end," Luciana said. "He was one of the most engaging faculty we had."

In addition to his wife, Carol, Gottesman is survived by sons, Adam and David, and three grandchildren. His family is hosting a celebration of his life at 10:30 a.m. Saturday at Metropolitan Ballroom, 5418 Wayzata Blvd., Minneapolis.