Here's why:
* Genes come in pairs: We inherit one copy of each gene from our mother and one from our father. These copies are called alleles.
* Dominant and recessive alleles: Some alleles are dominant, meaning they will always be expressed if present. Others are recessive, meaning they are only expressed if two copies of the recessive allele are present.
* Hidden trait: If an individual has one dominant allele and one recessive allele, they will express the dominant trait. The recessive trait is still present in their genes but is masked by the dominant allele.
Example:
* Brown eyes are dominant over blue eyes.
* If a person has one allele for brown eyes and one allele for blue eyes, they will have brown eyes because the brown eye allele is dominant.
* The blue eye allele is still present but is recessive and therefore not expressed. This makes blue eyes the recessive trait in this example.
