In humans, the gene for right-handedness (A) dominates over the gene for left-handedness (a). A left-handed woman marries a right-handed man. It is known that both fathers were left-handed. Determine the genotypes of all family members on the basis of “right-handedness / left-handedness condition”. What is the probability of the birth of left-handers in this family?
1. Genotypes and phenotypes of P: and mother – aa; father – Aa – because it is indicated that their fathers are left-handed (aa), which means that one gamete (a) both receive from their fathers.
2. Genotypes and phenotypes of offspring: Aa and aa – right-handed children 50% and aa – left-handed 50%;
3. The probability of giving birth to left-handed children is 50%.
Answer: mother – aa, father – Aa, probability – 50.
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