[Catalist] Genetics question for Bio/ Human Bio Teachers

[Greg Munyard]

Good morning folks

My colleagues and I are having some discussion around this question and I wondered if there is a consensus in the Bio/ Human Bio community on this:

"If II-8 (XnY) and II-9 (XNXn) have more children, what is the probability that they will produce an affected daughter?" (Genotypes not in the original question - had to be ascertained from a pedigree.)

One colleague's approach is to say that there is a 50% chance for producing a daughter and 50% chance that a daughter will be affected so the combination of these is a probability of 25%.

My approach is to say that there is zero chance for sons to be daughters so that they represent a null sample. Considering only daughters then the chance of an affected daughter is 50%.

Any guidance out there in the ether?

Regards

Greg Munyard
Senior Teacher - Science
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