He was from North Wales, PA, at the time he enlisted. I didn't find his parents or birth info, but did find confirmation that his mother was Lizzie/Elizabeth:
Source: Ancestry.com. U.S., Army Transport Service, Passenger Lists, 1910-1939 [database on-line]. The National Archives at College Park; College Park, Maryland; Record Group Title: Records of the Office of the Quartermaster General, 1774-1985; Record Group Number: 92; Roll or Box Number: 399
Name: Wallace William Keller
Departure Date: 3 May 1918
Departure Place: New York, New York
Address: 345 Elm St
Residence Place: North Wales PA
Mother: Lizzie Keller
Ship: Carmania
Military Unit: 109th Inf
Rank: Private
Service Number: 1235162
Notes: Company "A" 109th Infantry
He was a member of the First United Church of Christ in Quakertown, PA and was confirmed there on April 16, 1916.
Source: Ancestry.com. Pennsylvania and New Jersey, Church and Town Records, 1669-2013 [database on-line]. Lehi, UT, USA, Historical Society of Pennsylvania; Philadelphia, Pennsylvania; Historic Pennsylvania Church and Town Records; Reel: 528
Hope this helps a bit! :)