Apply the laws of probability and calculate the probability

Apply the laws of probability and calculate the probability the offspring of the cousin marriage of 1 x 6 will have the trait.
(enter a decimal fraction between 0.00 and 1.00)

Apply the laws of probability and calculate the probability the offspring of the cousin marriage of 1 x 6 will have the trait.
(enter a decimal fraction between 0.00 and 1.00)

Solution

The pedigree suggests that it is recessive autosomal heritance trait. The first generation (from left hand side) has male homozygous aa and female is homozygous AA. It is because all offspring (2^nd generation) have no disuse. The heterozygous Aa female of LHS who is married to the male of second generation (from RHS) is heterozygous Aa. It is because the offspring have one male diseased. He must have homozygous allele which only possible if come from both parents. Now the cross between both have offspring AA/Aa (1/3/4) and aa(2).

Aa x Aa = AA, aa, Aa

On the right hand side, the parent; female has aa and male has Aa. Female of 2^nd generation who married to a male (no disease), has aa genotype and the male has Aa genotype. It is because the offspring from both one female got diseased (which will come from both parents) and the female parent is diseased. So, the cross between both: Aa(5), aa(6), Aa(7).

Now cross between 1 x 6 which is if AA x aa

Offspring= Aa,; so there is 0% chances of having disease to any child

Number of recessive homozygous genotype/ total genotypes = 0/2 =0

If the 1 has Aa genotype then Aa x aa

Offspring = Aa, aa; so there is 50% chances of having disease to any child.

Number of recessive homozygous genotype / total genotypes = ½ = 0.50