**Some of the content on this page is out of date, please pardon us while we update it for accuracy.**

Below is a list of phenotypes easily identified in humans that follow the pattern of Mendelian inheritance. Look at yourself in the mirror to see if you carry the dominant or recessive alleles for these traits.

Mendelian Traits In Humans 

Cleft chin (dominant)		Chin without a cleft (recessive)
Cheek dimples (dominant)		No cheek dimples (recessive)
Free (dominant) earlobes		Attached (recessive) earlobes
Face freckles (dominant)		No face freckles (recessive)
No Hitchhiker's thumb (dominant)		Hitchhiker's thumb (recessive)
Widow's peak (dominant)		No Widow's peak (recessive)

The expression of traits, however, is often far more complicated than in those listed above or those which Mendel observed in his garden. Sometimes tens, or even hundreds of genes can play a role in just one trait! In some cases, genes can block or exaggerate processes in the cell which change the visible phenotype. In other cases, environmental factors such temperature, light, and nutrient levels influence the development of a phenotype. Below is a list of traits in humans involving interaction between multiple genes.

Non-Mendelian Traits in Humans

Eye color
Hair Color
Ability to roll tongue

References:

List of Mendelian traits in humans. In Wikipedia. Retrieved July 20, 2010, from https://en.wikipedia.org/wiki/List_of_Mendelian_traits_in_humans

Additional images via Wikimedia. Close up of iris by Petr Novák.