His research on family violence and child welfare helped shape government policy and social work practices nationwide.
His study, The Violent Home, was the first systematic investigation to provide empirical data on domestic violence.
Gelles responded forthrightly to prevent the public from purposefully distorting his research findings on family life.
For example, in response to father's rights groups, Gelles published "Domestic Violence: Not An Even Playing Field" to rectify what he calls a "significant distortion of well-grounded research data.
[5] Gelles's mother Evelyn was such a fan that she asked her ashes be left in the Boston Fenway Park field.
On visits to see his dying father, Jason noticed a small bag labelled “Fenway dirt.” It was a gift package colleagues gave Gelles when he stepped down from a deanship at Penn.
At the burial, Jason tossed the Fenway grit into his father's grave, an act baseball fans especially understand.