So for red hair this is my punnet square. My dad (on the top) is affected by the red hair gene so he has two lowercase R's, My dad gets two lowercase R's because the first lowercase R means that he is a carrier of the gene, and the second R means that he is affected so he is a red head. My mom (on the bottom) is a carrier of the red hair gene so she gets one lowercase R and one upper case R, She gets one lowercase R because she is a carrier of the gene, She is carrier because her grandma had red hair so that gene is in her blood. She gets a uppercase R because she isn't affected so she's not a red head.