Recessive alleles only show their effect if the individual has two copies of the allele (also known as being homozygous?). For example, the allele for blue eyes is recessive, therefore to have blue eyes you need to have two copies of the ‘blue eye’ allele.
Can recessive alleles be hidden?
The recessive trait is hidden in the heterozygous individual (Dd) if the other allele is inherited in a dominant fashion, and so this person is a called a “carrier” of the recessive allele, but does not manifest the disease or trait.
Where do recessive genes come from?
One gene in each pair comes from the mother, and the other gene comes from the father. Recessive inheritance means both genes in a pair must be abnormal to cause disease. People with only one defective gene in the pair are called carriers. These people are most often not affected with the condition.
What traits are dominant and recessive?
Dominant and recessive traits exist when a trait has two different forms at the gene level. The trait that first appears or is visibly expressed in the organism is called the dominant trait. The trait that is present at the gene level but is masked and does not show itself in the organism is called the recessive trait.
How can you tell if a trait is dominant or recessive?
The way people write out dominant and recessive traits is the dominant one gets a capital letter and the recessive one a lower case letter. So for eye color, brown is B and blue is b. As I said above, people have two versions of each gene so you can be BB, Bb, or bb–BB and Bb have brown eyes, bb, blue eyes.