Since I dont know the time period or location you are looking at for Joseph Reitz I can give you some ideas.
You might want to go look for church records that list his baptism date. Its possible that they listed his parents with him.
You might have to look for records in probate for his parents. That might show lineage. A death certificate will also names of known parents. Or Death notice in newspaper articles might list parents.
I looked in the NSDAR Patriot Index and did locate a Andreas Reitz/Ritz
Service: PENNSYLVANIA Rank: PRIVATE
Birth: 1-1-1755 PENNSYLVANIA
Death: 3-16-1837 NORTHUMBERLAND CO PENNSYLVANIA
Service Source: PA ARCHIVES SER.5 VOL-8 P.662,669
1) CAPT BENJAMIN WEISER NORTHUMBERLAND CO,
Spouse: 1) MARIE MARGARET BROSIOUS
Children: JACOB  ANNA MARIA HEPLER
PHILIP  ANNA WAGNER
It is possible to obtain a copy of a DAR application under RITZ, ANDREW. Use this URL for more information http://members.dar.org/apps/record_copy.cfm
Application papers of active, deceased, resigned, or dropped DAR members may be ordered for a fee of $10.00 per paper for electronic orders or $15.00 per paper for copies ordered by mail or by fax. Make sure you specify which child you view.
If there is anything else I can do please let me know.
This has been as a free look up service provided by a DAR volunteer.