>Question is... how hard would you try to confirm het status before giving up? Say you have a 50% chance of getting albino offspring from a het x albino crossing. How many "normal looking" offspring would you go through before declaring the original "potential het" to be a non-het?



I would keep trying until the probability is less than 1% that it's a heterozygote that hasn't produced any albinos simply through the luck of the draw. The way to determine that is figure out the probability of getting one normal, which in this case is 50% or 0.5. The probability of getting all normals is 0.5 to the nth power, where n is the number of babies.



Probability of getting all normals

1 baby = 0.5

2 babies = 0.5 x 0.5 = 0.25

3 babies = 0.5 x 0.5 x 0.5 = 0.125

4 babies = 0.5 x 0.5 x 0.5 x 0.5 = 0.0625

5 babies = 0.5 x 0.5 x 0.5 x 0.5 x 0.5 = 0.03125

6 babies = 0.5 x 0.5 x 0.5 x 0.5 x 0.5 x 0.5 = 0.015625

7 babies = 0.5 x 0.5 x 0.5 x 0.5 x 0.5 x 0.5 x 0.5 = 0.0078125



So in this mating, if I got seven or more babies, and all of them were normal, then I would class the possible het as a normal and move on to a new project.



The same method is used when breeding a possible het to a known het. Only the probability of getting a normal from this mating is 0.75. And the probability of getting all normals is 0.75 to the nth power. A calculator that can do powers is very handy for this sort of thing.



Paul Hollander

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