Inherited Traits

Inherited traits are features you get from your parents through your genes. Eye color, hair color, the shape of your nose, and whether you can roll your tongue are all inherited traits. They are passed down in tiny instructions called genes, which live inside almost every cell in your body.

Every person starts as one cell. That cell holds 46 chromosomes, which are long strands of DNA. You get 23 chromosomes from your mother and 23 from your father. Your genes sit on these chromosomes like beads on a string. Humans have about 20,000 genes in all. Some control the color of your eyes. Others decide how tall you might grow or what shape your earlobes have.

Because you get one set of genes from each parent, you have two copies of most genes. Sometimes the two copies disagree. One copy might say "brown eyes" and the other might say "blue eyes." When this happens, one gene usually wins. Scientists call the winning version "dominant" and the losing version "recessive." Brown eyes are dominant over blue eyes. That is why two brown-eyed parents can still have a blue-eyed child if they both carry a hidden blue-eye gene.

A monk named Gregor Mendel figured out the basic rules of inheritance in the 1860s. He studied pea plants in his garden. By counting tall and short plants over many years, he showed that traits pass down in clear patterns. Nobody paid much attention until long after his death. Today his rules are taught in every biology class.

Not every trait works the simple way Mendel described. Skin color, height, and hair color are shaped by many genes working together. That is why kids in one family can look very different from each other. Some traits also depend on the world around you. Your genes might allow you to grow six feet tall, but you also need good food and sleep to reach that height. Scientists call this mix "nature and nurture."

Some traits are not inherited at all. A scar from falling off your bike is not in your genes, so you cannot pass it to your children. Skills like reading, riding a bike, or speaking Spanish are also learned, not inherited. You might inherit a body that learns languages quickly, but you still have to do the work.

The next time you look in a mirror, think about what you see. Half of you came from one parent, half from the other, mixed in a brand new way that has never existed before.