I have no idea if the body can produce .02 Promille as a result of naturally produced alcohol, however at least two scientific papers have been written on the subject.
Lindiger, W., Taucher, J., Jordan, A., and Vogel, W. Endogenous production of methanol after the consumption of fruit. "Alcoholism: Clinical and Experimental Research", 1997, 21, 939-943
Phillips, M., Greenberg, J., and Martinez V., Ostrovsky, Y. M. Endogenous ethanol -- its metabolic, behavioral and biomedical significance. "Alcohol," 1986, 3, 239-247.
--Mik