Genetic counselors are one group of professionals who are equipped to answer questions like, "Why is my hair red?" Kaylee Henson, a genetic counselor and member of the Indiana Network of Genetic Counselors (INGC), provides the answer.
Hair color was once thought to be a simple genetic trait. However, more recent studies have led scientists to believe that hair color is actually much more of a complex genetic trait than originally thought!
Our bodies are made of billions of cells, which house our genetic information that is stored on structures called chromosomes. Each chromosome is made of DNA, which can be broken into smaller sections called genes. Genes are the instructions that tell our body how to function, like a recipe. Humans have 23 pairs of chromosomes, for a total of 46 in each cell. For each pair, we receive one copy from our mom and one copy from our dad.
Hair color is the result of many genes working together. These genes have the instructions to make pigments, called melanin. There are two main types of melanin: eumelanin—a brown-black color—and phaeomelanin—a red-brown color. Think of it like a painter, tinting his own paint to use on a painting. If the painter adds more phaeomelanin to his paint, it will be redder in color. If he adds more eumelanin, it will be blacker in color. Individuals with red hair are thought to inherit genes that produce more phaeomelanin than eumelanin.
Scientists have identified a key gene involved in melanin production, called melanocortin 1 receptor (MC1R), but they are still evaluating the role of several other genes that may be involved in pigmentation. Hair color depends on which versions of each of these genes an individual inherits and expresses. That explains why parents can have a different hair color than their children—or some families can have multiple children, each with a different color of hair!