 O'Hare was born in the Bronx, New York City, on February 12, 1931, one of three children born to Joseph O'Hare, a member of the New York City Police Department's Mounted Division, and Marie Enright O'Hare, a New York City schoolteacher and guidance counselor.He graduated from Regis High School in 1948.He entered the Jesuits on July 30 of that year.