J. Duncan was the son of James Calvin, Jr. and his wife, Gertrude Duncan How.

His mother, Gertrude, died in 1895 when he was 2 years old.
His father, James, died in 1900, when J. Duncan had just turned 7.

He married Marjorie I. Estes on June 6, 1914 in Alton, NH.
He was 21; she was 19 years old.
EW Ricker, clergyman, performed the ceremony.

Children include:
Gertrude Whitney How Palmer b 8/5/1914 Haverhill, MA
Helen M. How b 9/15/1918 Kingston, NH
James C. How
Charlotte D. How
William Edward How b 3/13/1920 Haverhill, MA

1900 Haverhill, MA Census:
[Cedar St]
Helen L. How, head, b Mar, 1832, NY, Wd, 68, 6/1
William E, son, b Jan, 1858, MA, S, 42, Stationer
Helen W, grand-dau, b Jan, 1890, ME, 10, at school
James D, grand-son, b Mar, 1893, MA, 7, at school
Margaret Noonan, 26, servant, b Ire

1910 Haverhill, MA Census:
Julia C. Howe, head, 78, Wd, b NY, 6/1, Own income
William E, son, 52, S, b PA, Retail stationary store
James D, grandson, 17, S, b MA
Julian Minehan, 29, servant, b Ire, housekeeper

1920 Merrimac, MA Census:
James D. How, 26, Commercial traveler, drugs
Marjorie, wife, 24
Gertrude W, dau, 5
Helen M, dau, 3 11/12
James C, son, 2 9/12
Charlotte D, dau, 1 3/12

1940 Merrimac, MA Census:
Duncan, 45, Supervisor, Federal Community
Marjorie, 44
James C, son, 22, Clerk, retail grocery
Charlotte D, dau, 21, Stenographer, channel factory
William E, son, 20, Salesman, automobile

Draft Registration, Sept., 1917:
James Duncan How
8 Cedar St, Haverhill, MA
DOB: 3/17/1893, Haverhill, MA
Salesman, William E. How, 27 Washington Square, Haverhill
Married; wife and three children
Physical Desc: Medium height and build with gray eyes and dark brown hair.

Draft Registration, 1942:
James Duncan How
DOB 3/17/1893 Haverhill, MA
Age 49
Res: 45 Merrimac St, Merrimac, MA
Federal Surplus Commodities
Kin: Mrs. JD How, same address