How does genetics work?

What Is Genetics?

Genetics is the study of how different qualities, called traits, are passed down from parents to child. Genetics helps explain what makes you unique, why family members look alike, and why some diseases run in families. When we trace the paths of these qualities, we are following packages of information called genes.

How Do Genes Work?

Your body is made up of trillions of tiny cells. Almost every cell in your body has a nucleus, a sort of headquarters that contains your genes. Your mix of genes is unique to you—even your full brothers or sisters have a slightly different mix. Genes are instructions for building the parts of your body and doing the work that keeps you alive, from carrying oxygen to digesting to food and everything else we do. The genes are grouped into collections called chromosomes. Most humans have 23 pairs of chromosomes.

Where Did You Get Your Genes?

You got all your genes from your parents. For each pair of their chromosomes, you get one chromosome from your mother and one from your father. When the egg and sperm cells come together, they create the full set of 46 chromosomes or 23 pairs.

So why aren’t your genes exactly the same as your siblings?  Like you, your parents each have two copies of their chromosomes, which they got from their parents. When sperm and eggs are created, pairs of chromosomes separate independently and sort themselves at random into two eggs cells in your mom or two sperm cells in your dad.  You might get one chromosome in one pair from your mom, and your sister might get the other chromosome from that pair. This means that there are 8,388,608 possible variations of egg and sperm.  It’s really a wonder we look like our parents at all!