|  Recessive and Dominant Inheritance
    
 Legend: 
 Mechanisms of recessive and dominant inheritance.
 Both parents carry a
  normal gene (N), and a faulty, recessive, gene (n). The
  parents, although carriers, are unaffected by the faulty gene. Their
  offspring are affected, not affected, or carriers. This type of inheritance
  was first shown by Mendel. One parent has a single,
  faulty dominant gene (D), which overpowers its normal counterpart (d),
  affecting that parent. When the affected parent mates with an unaffected and
  non-carrier mate (dd), the offspring are either affected or not
  affected, but they are not carriers. |