An individual must inherit two non-functioning CF genes – one from each parent – to have CF. If both parents are carriers there is a 1 in 4 (25 percent) chance that both will pass on the non-functioning gene, which would result in a pregnancy affected with cystic fibrosis.
This means that the mothers green eyes are recessive alleles and the fathers brown eyes are dominant alleles. The blue eyed puppy is blue eyed because there must have been a gene in the mothers or fathers past generation.
