[Catalist] Genetics question for Bio/ Human Bio Teachers

[Andrew Williams]

On 2017-10-26 9:51 AM, Greg Munyard wrote:

> 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 /(X^n Y)/ and II-9 /(X^N X^n )/ 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.)

The wording of the question is too ambiguous. It really needs to read 
like either

"If II-8 /(X^n Y)/ and II-9 /(X^N X^n )/ have another child, what is the 
probability that child will be an affected daughter?"

or

"If II-8 /(X^n Y)/ and II-9 /(X^N X^n )/ have another daughter, what is 
the probability that she will be affected?"

As it is, not only is the distinction between those two cases unclear, 
the question actually says "more children", in the plural, not singular. 
If they were to have _ten_ more children, the chances of one of those 
children being an affected daughter are much higher than 25% or 50%.

Andrew