Insufficient pre-DSB coalignment in the hybrids may enhance the probability of entanglements between chromosomes and increase the occurrence of ectopic recombinational intermediates between nearly homologous sites of nonhomologous chromosomes. Because the sequence homology matching in these intermediates is apparently low, they should be less stable. The unwanted DNA connections tend to be eliminated by the mismatch repair system59 and active chromosome movements62. We propose that the balance in stability between “wanted” and “unwanted” connections is impaired in hybrids, due to a decrease of sequence homology between the homologous regions of the parental species. This leads to variability between oocytes in the number and size of regions involved in multivalents.