Robert D. Putnam’s daughter raised his granddaughter, Miriam, in a privileged, upper-class home. Miriam graduated from high school, is on her way to college and has never used drugs.

His friend’s granddaughter, “Mary Sue,” grew up in a lower-income area, where she sold marijuana, went to a juvenile detention center and dropped out of high school.

For Putnam, these parallel narratives indicate a larger issue encasing income inequality: Communities are no longer willing to help one another do better.

A visiting professor from Harvard’s School of Public Policy, Putnam visited Pitt Monday afternoon to summarize and discuss the research presented in his newest book, “Our Kids: The American Dream in Crisis.” One-hundred-fifty people attended the lecture, hosted by the Pitt Honors College and the Dick Thornburgh Forum for Law and Public Policy, where Putnam illustrated the alienating effects of income inequality.

“Helping Mary Sue would help Miriam,” Putnam said at the lecture. If communities focused on funding public programs for children, Putnam said, students like Mary Sue would thrive, not fall between the cracks.

Putnam’s 14th book narrates how income inequality hurts all of America.

“America has become, in the last 40 years, less a ‘we’ society and more an ‘I’ society,” Putnam said in an email after the event. “That applies to all classes, but especially those of us with more privilege.”

Putnam’s lecture examined his hometown of Port Clinton, Ohio — which is also the focus of his book — where the child poverty rate has risen to 50 percent between 2008 and 2012, according to Putnam. A few miles away, in affluent Catawba Island, child poverty has remained at a constant zero percent.

In the opening chapter of his book, Putnam tells the story of “Joe,” Mary Sue’s grandfather, who graduated from high school with him in Port Clinton.  After high school, Putnam said Joe chose to work in Port Clinton rather than go to college. His kids followed in his path.

For years, Joe’s family made more money than Putnam did as a college professor — until the local economy collapsed.

Now, Mary Sue, the daughter of a divorced couple, has had a far more difficult life than Miriam.

Putnam used stories, such as Joe’s and Mary Sue’s, to show that the lack of educational and community programs stunts not just one generation’s potential, but future generations’ as well.

Among anecdotes, Putnam presented facts and figures, some of which brought tears to the audience’s eyes.

In the United States, for example, high-intelligence students from low-income families have a 29 percent chance of graduating from college, while low-intelligence students from high-income families have a 30 percent chance of graduating.

For Kathryn Vargas, a 2010 Graduate School of Social Work grad who attended the lecture, Putnam’s research is the start of a larger conversation about income inequality.

“It’s the kind of conversation that the mainstream community isn’t having,” Vargas said. “It’s important that someone has captured the information like this.”

Putnam’s research doesn’t stop at income inequity. While interracial and interreligious marriages have increased, interclass marriage rates have decreased, which Putnam said indicates the growing class division within American cities, such as neighborhoods in New York.

Ellie Pfeuffer, a 2010 Graduate School of Public and International Affairs alumna, said Putnam’s speech brought to mind the debt associated with college students.

“It is an important issue because of the disparity across the country as we see increasing debt among students,” Pfeuffer said.

Jeff Hyams, a Pitt Class of 1979 graduate who attended the lecture, said as someone who is also from Port Clinton, Putnam’s hourlong talk changed the way he thought about impoverished people.

“I [had] believed that claiming poverty is responsible for the condition we find ourselves in is foolish,” Hyams said. “After what he has presented today, I feel that I absolutely must rethink that position.”