Hi Jenn, You didn't mention what your father's first name is but I found a George Turnbull born in 1928 and he is the son of Robert W. and Elloen Turnbull.
This is on the 1930 U.S. Census, Chicago (Districts 501-750),Cook, Illinois. Enumeration District No. 610, Family No.19, NARA Publication T626,roll442, Film No.2340177, Digital Folder No. 4584243, Image No. 00394.There are also a couple of other names mentioned, a Dunede Kimball age 20 from Ireland and Thomas Andrew age 22 also from Ireland.They were borders but I don't know if they are related.It is interesting because one of the names I am researching is Andrew!I hope this is of some help.Let me know if I can be of anymore help.