When John Merlin "Jack" Welsh was born on 6 December 1912, in Zwingle, Dubuque, Iowa, United States, his father, John Henry Welsh, was 30 and his mother, Susan Ansie Peters, was 26. He had at least 1 son and 1 daughter with Myra Cox. He lived in Washington Township, Dubuque, Iowa, United States in 1920 and Table Mound Township, Dubuque, Iowa, United States in 1930. He died on 14 June 1991, in Dubuque, Dubuque, Iowa, United States, at the age of 78, and was buried in Key West, Dubuque, Iowa, United States.