Very good, Dave. This is the technique called forkline, the arithmetic method, branching system, and I don't know how many other names. An automobile odometer uses it on rotors to produce 100,000 unique number combinations for mileage. My genetics prof taught it to all his students. I can do a two-locus forkline in half the time and with greater accuracy than a two-locus Punnett square. Three and four locus forklines are not particularly difficult. I've done a three-locus Punnett square once. Never again! That is why I have written more than once that only a masochist uses a Punnett square for more than 1 locus.

The forkline technique can substitute even for a one-locus Punnett square. And it is not limited to two choices. The technique can do straight genotype problems, straight phenotype problems and problems that are a mix of genotype and phenotype.

A forkline is much easier to turn into a computerized genetics program than a Punnett square is. As far as I know, this is the basis for the Genetics Wizard.

Paul Hollander

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