When William J. Jenkins was born in August 1865, in Wales, United Kingdom, his father, Evan Jenkins, was 20 and his mother, Margaret Williams, was 22. He married Jemima Harris on 24 December 1888, in Scranton, Lackawanna, Pennsylvania, United States. They were the parents of at least 1 daughter. He died in 1935, in Scranton, Lackawanna, Pennsylvania, United States, at the age of 70, and was buried in Washburn Street Cemetery, Scranton, Lackawanna, Pennsylvania, United States.