When the alleles present for a trait are the same, they are called homozygous.

Here's a breakdown:

* Alleles: Different versions of a gene.

* Homozygous: Having two identical alleles for a trait.

* Heterozygous: Having two different alleles for a trait.

For example, if someone has two alleles for brown eyes (let's say "B"), they would be homozygous for eye color.