An Etymological Dictionary of the German Language/nähren
nähren, vb., ‘to nourish, support, foster,’ from MidHG. nęrn, nęrigen, OHG. nęren, nęrian; prop. causative of genesen, hence ‘to cause to recover, make healthy, heal, rescue, keep alive.’ The modern gene is found as early as MidHG. The word corresponds to OSax. nęrian, AS. nęrigan, Goth. nasjan, ‘to rescue.’ The change of s (for z) to West Teut. and Scand. r at the end of the stem in causative vbs. is normal (comp. lehren); allied to OIc. nœ́ra. See nahrhaft and genesen.