mendelian
In many instances, the relationship between genes and inheritance is more complex than that which Mendel found. Nevertheless, geneticists have since found that Mendels findings can be applied to many organisms. For example, there are clear patterns of Mendelian inheritance in humans. These include the inheritance of normal characteristics and characteristics that occur less often. Easily observable Mendelian traits in humans include free ear lobes in most people the ear lobes hang free dominant , whereas the attached earlobe is recessive , hitchhiker's thumb a straight thumb is dominant, while a bent thumb is recessive , widow's peak a hairline with a distinct point in the middle of the forehead is dominant, while a straight hairline is recessive , dimpled chin a cleft in the chin is dominant, whereas the absence of a cleft is recessive , and mid-digital hair hair on any middle segments of the fingers is dominant . Of course, many severe human phenotypes are inherited in a Mendelian fashion including Phenylketonuria PKU , cystic fibrosis, Huntington's disease, hypercholesterolemia, and sickle-cell anemia. These are termed genetic disorders and will be discussed in additional concepts.