No, the thumbprints on the left and right hand are not identical. Even if they are the same type of finger print (loop, arch, or whorl) and they look the same, they are not exactly the same. Fingerprints are partially genetically determined, and partially determined as a fetus develops, although the exact mechanism for fingerprint formation is not completely understood. If fingerprints were completely determined by genetics, the left and right thumbprints might be identical, but because other factors are involved, every fingerprint turns out differently. The complex formation of fingerprints means that even identical twins have different fingerprints.