Having a long neck is dominant to having a short neck.
Both of Adam's parents have long necks, but Adam has a short neck.
What is the BEST explanation for why Adam has a short neck?
Three of Adam's grandparents had short necks.
Adam's father is a carrier of the recessive gene for a short neck.
Adam's mother is a carrier of the recessive gene for a short neck.
Each of Adam's parents have a recessive gene for having a short neck.