Draw a pedigree to show the inheritance of the trait of rolling the tongue. Given the following family history: Grandpa Snow is a tongue roller but Grandma Snow is not. They have four children, 2 sons and 2 daughters, who are all rollers. Their last daughter, Judy, married John Flake. John's parents are both rollers, but John's two sisters are non-rollers. John is a roller. John and Judy Snow-Flake have three children named Crystal Snow-Flake (non-roller), Delicate Snow-Flake (roller) and Jake Snow-Flake (roller). Determine the possible genotypes of each individual.
