Human beings are born with 46 chromosomes.  These are thread-like structures that carry the genetic instructions that over time develop a one-celled embryo into a 100 trillion-cell human adult.

Each person inherits 23 chromosomes from their biological mother and 23 chromosomes from their biological father.

Genetically, each person is 99.9 percent identical to the 6 billion other humans on the planet. But that seemingly small variation in our genetic makeup - the 0.1 percent - can have dramatic consequences on physical and mental health and appearance. Researchers suggest that genetics play a role in our personalities.

One important thing you can do for your health and your family's health is to collect your family health history. Knowing what diseases have affected your blood relatives can help your healthcare provider gauge your risk for certain diseases and suggest ways to reduce that risk.

For more information on what scientists know about genetics, see Medline Plus .

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