Ignore probability because we already know CF is recessive.

Michael chooses to skip probability:

Michael: ‘Maybe we can just note that CF is recessive, so the only big deal is if the child ends up aa.’

Dr. Antoniou (shaking his head): ‘That oversimplifies matters. We need to know how often ‘aa’ might occur in each child, or if a child could be a carrier. Probability helps provide clear insight.’