The gene that displays its trait in the presence of a dominant trait is called a recessive gene.

Here's how it works:

* Dominant genes: These genes express their trait even if only one copy is present. We represent them with a capital letter (e.g., "B" for brown eyes).

* Recessive genes: These genes only express their trait if two copies are present. We represent them with a lowercase letter (e.g., "b" for blue eyes).

Example:

Let's consider eye color. Brown eyes are dominant over blue eyes.

* BB: Brown eyes (dominant)

* Bb: Brown eyes (dominant)

* bb: Blue eyes (recessive)

As you can see, even if someone carries one copy of the dominant brown eye gene (B), they will have brown eyes. They only have blue eyes if they have two copies of the recessive gene (bb).