Problem: Ann's family has a history of cystic fibrosis, a recessive genetic disease. In the pedigree below, family members who are afflicted with the disease are shown in red. Members who are unafflicted may or may not be carriers. Which of the given family members can be identified definitively as unafflicted carriers of cystic fibrosis?

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Cystic Fibrosis (CF) is an autosomal recessive disorder. Thus, it has no correlation with the sex chromosomes, whatsoever. Based on the diagram, 2 out of 3 of the children of the grandparents have cystic fibrosis. This makes both grandparents carriers despite being unafflicted. Ann's uncle has a chance of not being a carrier but the chance is small (25%) and not definitive. 

Male cousin (1) is already afflicted. This immediately puts him out of the list.

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Problem Details

Ann's family has a history of cystic fibrosis, a recessive genetic disease. In the pedigree below, family members who are afflicted with the disease are shown in red. Members who are unafflicted may or may not be carriers. Which of the given family members can be identified definitively as unafflicted carriers of cystic fibrosis?