If father has hemophilia, mother is a carrier of the disease, then what is the probability of having a normal daughter ?

My question: Should the probability of having a daughter be also multiplied ? Should the answer be 0.5 or should it be 0.25 ?

  • 1
    $\begingroup$ Unfortunately, the question is ambiguous. $\endgroup$ Jan 25, 2014 at 8:11
  • $\begingroup$ @ChinmayKanchi umm..I am not able to understand how this is ambiguous.Could you please elaborate ? $\endgroup$
    – user4058
    Jan 25, 2014 at 9:26

1 Answer 1


I can't understand what you mean by "Should the probability of having a daughter be multiplied?" But yes, the probability of having a normal daughter is 0.25, but she will be a carrier like her mother.

Let H represent normal allele for blood clotting (dominant); h represent allele for hemophilia, XY represent the male chromosomes and XX represent the female chromosomes.

Parental Phenotypes :

   Normal female(carrier) x Hemophiliac male

Parental Genotypes (2n) :

   X(H)X(h)         x     X(h)Y

Gametes (n) :

   X(H)     X(h)    x   X(h)     Y

Possible Outcomes :

X(H)X(h) - A normal female, carrier.

X(H)Y - A normal male.

X(h)X(h) - A hemophiliac female.

X(h)Y - A hemophiliac male.

So probability of having a normal daughter, that is X(H)X(h) is 0.25.

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    $\begingroup$ I couldn't find a way to write superscripts, so I put the alleles in parenthesis. Its usually written in superscript. Hope this helps. :) $\endgroup$ Jan 25, 2014 at 10:48

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