Each person receives one copy of a gene pair from his mother and one from his father. Even though you get half of your genes from your mother and half from your father, each of your parents contributes to all your traits . For the each trait, there are different versions of a gene. Different versions of a gene are called alleles . Although you can have two different alleles, you usually only express one of them.
Alleles can be dominant or recessive.
Dominant alleles are always expressed, regardless of what the other allele is that a person has. Recessive alleles are only expressed if both of a person's alleles are recessive. If a person has one dominant allele and one recessive, he is called a carrier . An example of this is albinism. Albinism is a condition where a person does not produce any melanin, the protein that gives color to our skin, hair and eyes.