One of each pair comes fromour mother and the other from our father. In turn, we pass only one genefrom each pair to each of our children. Which gene we receive from a parentis determined randomly. Just as when we flip a coin, whether it comes upheads or tails is a random event. When the genes from our mother and father come together in the fertilizedegg cell, they arrange themselves in pairs.
Genes carry the necessary informationto cause that single cell to grow into a human being.
Occasionally, something happens that causes a gene to change. Geneticistscall this a mutation. It is estimated that each of us have several mutatedgenes. Most of the time these mutations have no effect on the individual,but sometimes they do. However, this person will be a carrier of UsherSyndrome.