Genetic Probability (Binomial Expansion)

  1. 1. The problem statement, all variables and given/known data

    I'm stuck on a problem with two variables in it. The question wants to know what's the probability of getting 2 boys and 2 girls, with one of the boys being albino. They say one parent is albino and the other is a heterozygous carrier, so the change of getting it is 50% in the children.
    So by binomial expansion, it's 1 4 6 4 1. I know the two girls and two boys is the middle term with 6(p^2)(q^2) but with q and p being getting a boy or girl at .50 each. But how do I encompass the albino probability in this? Multiply each child by .50?

    2. Relevant equations

    (p^4)+4(p^3)(q)+6(p^2)(q^2)+4(q)(p^3)+(q^4)

    3. The attempt at a solution
    I can easily find the probability of getting two girls and two boys, I would simply use the 6(p^2)(q^2) with p and q being .50 respectively. I just don't know how to factor in the albino part.
     
  2. jcsd
  3. AGNuke

    AGNuke 456
    Gold Member

    Something like that. You should multiply with another binomial probability regarding the 4 children with "albino chromosome".
     
  4. Ygggdrasil

    Ygggdrasil 1,691
    Science Advisor

    It might be easier to calculate the probability that the two girls lack albinism and the probability that one of the boys has albinism.
     
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