Sexually reproducing beings inherit a bit of DNA called a chromosome from their mother and another bit from their father for each trait that they may eventually have. So, one might get a blue eye bit from one parent and a brown eye bit from another parent. When two bits of instructions for the same trait exist, they are called alleles of one another.
In humans, there are forty-six chromosomes made up of twenty-six from one parent and twenty-six from another. The chromosomes pass on information about how to build the body because they are made up of molecular strings of coded instructions called genes. The selection of which gene instruction or allele will actually dominate has something to do with random chance and with the ability of one to override the other. For example, the brown eyed allele will always be dominant. The other allele does...
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