prepotency \pree-POTE-n-see\ (noun) - 1 : The quality or condition of having superior power, influence, or force; predominance. 2 : (Biology) The capacity, on the part of one of the parents, as compared with the other, to transmit more than his or her own share of characteristics to their offspring.
"The prepotency of a Lepage stud is such that three of five colts are born blue roan. Of those three, two will have a star on the forehead; but the third will be the total blue of the orignial mustang." -- Robert Kroetsch, 'The Studhorse Man'
Prepotency is from Latin praepotentia, from prae-, "before" + potentia, "power," from potens, "able, powerful," present participle of posse, "to be able."