Ask why you look the way you do, and the answer has two parts. Kids often look a bit like the people in their family, but not exactly like any one of them. Something else is at work too.

The first part is heredity. Heredity is how traits get passed down from parents to their children. Looks such as eye color can run in a family, which is why a child can seem to have a grandparent's eyes.

Heredity does not make copies. Brothers and sisters from the same two parents each get a different mix, so they are not exactly alike. Kids with the same parents do not always look alike, even in one house.

It can also give a surprise. Parents with blue eyes can have a child with brown eyes. It is not common, but it happens. Identical twins, by contrast, look very similar to each other.

The second part is how a person lives. Some traits come from the way a person lives, not from family. These are called acquired traits. Where and how a child grows up, such as at home and at school, helps shape who the child is.

Height shows the two parts together. How tall a person grows depends on the family they come from and also on what they eat and how healthy they are. What a person eats and how much they exercise can change how they look and grow.

A child who eats well and stays active is likely to grow taller than a child with a poor diet. Looks can come from family and from surroundings together. Not everything about a person is decided by the body's instructions alone.

Families are made in more than one way. Some children join a family by adoption. An adopted child becomes a full and permanent member of that family, and has the same legal rights as a child born into the family.

A blended family, also called a stepfamily, forms when two people make a life together with their children. In a stepfamily, in an adoptive family and in a family joined by birth, a child is part of a family.

So the question has a fuller answer than one parent's nose or another's eyes. Part of how you look came down in your family. Part of it comes from your surroundings and the way you live.

Words to know

• heredity: traits passed down
• traits: features
• acquired: gained by living
• surroundings: what is around
• stepfamily: a blended family