Grant was born in Stevensville, Bradford County, Pennsylvania; his family moved to Massachusetts when he was approximately 5 years of age.
Years later, he wanted to sell people what they needed at prices they could afford, with only a modest profit.
He received honorary Doctor of Laws degrees from Bates College in Maine and the University of Miami.
Grant was the founder of the Grant Study, which was a longitudinal study of Adult Development at Harvard Medical School beginning in 1938 that followed 268 Harvard educated men in order to identify predictors of healthy aging.
The study found that alcoholism was the leading cause of divorces, correlated strongly with depression and neurosis, and when combined with the negative effects of smoking cigarettes, was determined to be the single greatest contributor to early morbidity and ultimately death.