10 Human Traits of Simple Inheritance - P2
5. Facial Dimples: Not sure if you have them? Smile! Dimples are a (very cute) facial muscle deformity that results in an indentation in the cheek. With dominant phenotype, you may have a dimple on one side, or both.

Dominant (have it) ___. 
Recessive (don't have it) ___.

6. Eye Color: Eye color, as well as hair and skin, is a complex trait; not a case of simple inheritance. The main pigment is melanin, and the more melanin, the darker the color. Although the genetics of eye color is complex, alleles for production of melanin dominate those for lack of melanin. So if we evaluate eye color as brown (dominant) or non-brown (recessive), it can be treated as a characteristic of simple inheritance.

Dominant (have it) __.
Recessive (don't have it) ___.
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Young man with prominent facial dimples. 
(Thanks for the pic Jack. 
Your dimples rock!)
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7. Free Earlobe: The dominant trait is for lobes to hang free, a bit of lobe hanging down prior to the point where the bottom of the ear attaches to the head. With the recessive phenotype, the lobes are attached directly to the head, leaving less room for fabulous earrings.

Dominant (have it) ___ Recessive (don't have it) ___. 

8. Hand Clasping: Clasp your hands together (without thinking about it!). Most people place their left thumb on top of their right and this happens to be the dominant phenotype. Now, for fun, try clasping your hands so that the opposite thumb is on top. Feels strange and unnatural, doesn't it?

Dominant (have it) __ 
Recessive (don't have it) ___.
9. Mid-digital Hair: Some people have hair on the middle segment of one or more of their fingers, while others don't. Having any hair there at all means that you have the dominant phenotype. Complete absence of hair is recessive.

Dominant (have it) __ Recessive (don't have it) ___.

10. Tongue Rolling: If you have the ability to roll the sides of your tongue upwards to form a closed tube, you have the dominant phenotype for this motor skill. Those who are not dominant for this trait cannot roll their tongue, no matter how hard they may try.

Dominant (have it) __ Recessive (don't have it) ___.

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Tongue Rolling Dominant Genetic Trait
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Sources and Resources
  • Thorpe ed. (2007) Biology 120 Lab Manual. Grand Valley State University.
  • Doezema, B. (2006) Biology 101 Lab Manual. Grand Rapids Community College. 

Hand Clasping Left Thumb On Top Is Dominant
​Page last updated: 10/2017
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Young man with prominent facial dimples
As opposed to an attached earlobe, a free earlobe has a nice little dangly bit at the bottom. 
Free earlobe: As opposed to an attached earlobe, a free earlobe has a nice little dangly bit at the bottom.