Boylan married Kathleen E. "Kathy" Costa on July 1, 1961. They had two sons and three daughters. Both sons, one daughter and a grandson graduated from West Point. Their son Colonel Gregory L. Boylan has made a military career teaching at West Point, following in footsteps of his uncle Brigadier General John J. Costa (May 7, 1925 – August 6, 2013) who retired on May 31, 1989, as the last veteran of
World War II on active duty in the U.S. Armed Forces. Boylan was a
cantor at his local
Roman Catholic church, the Sacred Heart of Jesus Catholic Church. Boylan resided in
Milledgeville, Georgia, with his wife. He died there on November 12, 2023, at the age of 87. ==References==