In humans, common examples of inherited traits include hair, skin and eye color, hair type, finger and toe length, dimples, freckles, body type, height, hand dominance, ear shape, mathematical aptitude and susceptibility to certain diseases, such as color blindness, cystic fibrosis and sickle cell anemia. The inherent traits of an individual are determined by the smallest functional unit of heredity known as a gene.
Approximately 25,000 to 35,000 genes are present in a single cell in the human body. These genes carry the characteristics and attributes that are inherited by an offspring from its parents. Not all traits that a person acquire are inherited. Some traits are learned and developed, such as the ability to run, walk, swim, speak and drive a car.