Living things make more of their own kind, one of the The Characteristics of Life. Offspring look like their parents in some ways but not in others. To see why, first sort traits into two kinds.
Key idea
An inherited trait is passed from parents to offspring through genes, like eye color, the shape of a leaf, or a dog's coat pattern. An acquired trait comes from experience or the environment during a lifetime, like a scar, a skill, a language or a pierced ear. Acquired traits are not passed on through genes.
Why it works
Offspring get their genes from their parents' cells. Exercise, injuries and lessons change the body or the brain, but they do not change the DNA a parent passes on. So a weightlifter's child starts with ordinary muscles, and a parent who learns French has a baby who still has to learn it.
Worked example: Sort it
A plant grows tall in a sunny garden. Its twin, from a cutting of the same plant, stays short in deep shade. Is the height difference inherited or acquired?
- The two plants have the same genes (one was grown from a piece of the other).
- The difference came from the light they got.
Answer: Acquired: it comes from the environment.
Worked example: Both at once
Height in people depends on genes and on food and health while growing up. Is height inherited or acquired?
- Tall parents tend to have tall children: genes matter.
- A child who gets too little food may grow less than their genes allow: environment matters.
Answer: Both. Many traits come from genes and the environment working together.
Common mistake
Students think a skill or an injury of a parent can be inherited, such as a weightlifter's muscles or a parent's piano skill. Ask: did the trait come from genes, or was it gained during the parent's life? Only traits coded in genes are passed on.