A phenotypically normal woman with an abnormally long chromo-some 13 (and a normal homolog of chromosome 13) marries a phe-notypically normal man with an abnormally short chromosome 11 (and a normal homolog of chromosome 11). What is the probability of producing an offspring that will have both a long chromosome 13 and a short chromosome 11? If such a child is produced, what is the probability that this child would eventually pass both abnormal chromosomes to one of his or her offspring?