Here's why:

* Genes: Genes are segments of DNA that contain the instructions for building and maintaining an organism.

* Alleles: Alleles are different versions of the same gene. You inherit one allele from your mother and one allele from your father for each gene.

* Traits: Traits are characteristics that are passed down from parents to offspring, such as eye color, hair color, or height.

The combination of alleles you inherit determines the trait you express. For example, if you inherit a brown eye allele from your mother and a blue eye allele from your father, your eye color will be brown (assuming brown is the dominant allele).