In humans, there is a gene that controls formation of muscles in the tongue that allow people with those muscles to roll their tongues, while people who lack those muscles cannot roll their tongues. The ability to roll one’s tongue is dominant over non-rolling. The ability to taste certain substances is also genetically controlled. For example, there is a substance called phenylthiocarbamate, which some people can taste, while others cannot. Let’s let R represent tongue rolling, r represent a non-roller, T represent ability to taste PTC, and t represent non-tasting.

Suppose a woman who is both a homozygous tongue-roller and a non-PTC-taster marries a man who is a heterozygous tongue roller and is a PTC taster, and they have 12 children, how many of those 12 would you expect to be non-tasters, who are homozygous for tongue-rolling?