Secondary sources call him "Peter John," but I'll wager it was John Peter (Johann Pieter).  In German naming practice, the middle name was the call name, while the first name was a saint's name, and Johann was, by far, the most-used saint's name (see Charles Kerchner's German Naming Practices).

1.  Jordan R. Dodd, ed.  1993.  KY, NC, TN, VA, WV Marriages:  Early to 1850.  Liahona Research, Orem, UT (Broderbund CD-229):  subjects' marriage not found.

2.  Census Index:  Colonial America, 1607-1789 (Broderbund CD-310):

1741	Laam, Conradt	PA	Philadelphia Co.	Philadelphia
1748	Lam, Johannes	PA	Philadelphia Co.	Philadelphia
1750	Lamb, Johanes	PA	Philadelphia Co.	Philadelphia
1758 Residence List	Lamb, John	MD	Maryland Colony		p. 138
1762-67	Lamb, Peter	NC	New Hanover Co.
1779-80 Tax Lists	Lamb, John	NJ	Essex Co.	Newark Twp.
1781-89 Tax Lists	Lamb, John	NJ	Gloucester Co.	Gloucester Twp.
1782 (census)	Lamb, John	VA	Orange Co.		p. 040
1787 Tax List	Lamb, John	VA	Charles City Co.
1788 Residence List	Lamb, John	OH	Northwest Territory

One or more of these might be our subject or his father.  (The Philadelphia records are usually of immigrants taking an oath of loyalty; Philadelphia was a major port of entry for Germans in the 18th century.)

2.  Census Index:  U.S. Selected Counties, 1790 (Broderbund CD-311):  not found, but the 1790 VA census was destroyed, and there was no Federal Census in Ohio (it was not yet a state).

3.  Census Index:  U.S. Selected Counties, 1800 (Broderbund CD-312):  there was no 1800 Federal Census in Ohio (it was not yet a state), but tax lists are substituted on this CD, where available.  Our subject is presumably deceased, but these apparent kin show up on the Fairfield Co., OH, tax lists:  George LAMB, Jacob LAMB, John LAMB, and Joshua LAMB.

4.  WorldConnect / Ancestry World Trees (online at RootsWeb.com/Ancestry.com).