There is a simple system for evaluating 3-factor crosses 1)Group recombinant classes into reciprocal pairs 2) The most frequent pair is the parental classes 3)Derive the gene order from the least frequent pair, which are the double cross over classes 4)The single crossover frequency for the two intervals can be obtained by adding the frequency of each of the single crossover class pairs to the frequency of the double crossover class pair. (In the present example the double crossovers are so rare that their inclusion doesn't matter)There is a simple system for evaluating 3-factor crosses: 1) Group recombinant classes into reciprocal pairs. 2) The most frequent pair is the parental classes. 3) Derive the gene order from the least frequent pair, which are the double cross￾over classes. 4) The single crossover frequency for the two intervals can be obtained by adding the frequency of each of the single crossover class pairs to the frequency of the double crossover class pair. (In the present example the double crossovers are so rare that their inclusion doesn’t matter). sh cn vg