Blue Eyes, Recessive is Absence of Melanin in Iris

10 Human Genetic Traits of Simple Inheritance 

Which Do You Have?


The most fun way to learn a little about genetics is to understand heredity first hand, your own heredity; and you can do that by examining the actual dominant and recessive traits that you possess.

Article Summary: Which traits did you inherit from your mother; from your father? Take this simple genetic quiz and learn about the genes that you possess.
10 Human Genetic Traits of Simple Inheritance
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Some Genes Mask the Expression of Other Genes
In some instances, the version of a gene that you get from one parent may block the expression of the version of that same gene you received from the other parent. 
Instructor's Corner
Girl with dimples, cleft chin and blue eyes.
Girl with cleft chin, dimples and blue eyes (no melanin).
Learn about Achoo Syndrome & Eyesight
Go to PAGE 2 >


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Genetic Complete Dominance Quiz
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Genes from Mom & Dad Determine Your Traits
You are a diploid organism, meaning that you received one set of genes (called alleles) from your father and the other set of alleles from your mother. 

The combination of these pairs of genes that you've inherited is called your "genotype." The genotype determines the actual traits (called the "phenotype") that you have; such as eye color, nearsightedness, and whether or not you have dimples.

Examples of Simple Inheritance of Traits that Show Complete Dominance
The next two pages of this article explain the inheritance of several genetic traits, including: 
  • facial dimples
  • bent little finger
  • eye color
  • hand clasping
  • early onset myopia
  • cleft chin
  • achoo syndrome

plus a printable heredity assignment based on this article, for students to complete.

Brown eyed son of brown eyed mother and green eyed father.
Blue eyed daughter of brown eyed mother and green eyed father.
Brown eyed mother and green eyed father produced one brown eyed child and one blue eyed child.
Brown-eyed mother and green-eyed father produced one brown eyed child and one blue eyed child. Because this couple was able to produce a blue eyed child, the mother is heterozygous for brown eyes (She has 1 brown and 1 non-brown allele).
that you received from your mother masks the expression of the blue eye, recessive allele. It is kind of like the game Rock, Paper, Scissors, but in this case, brown beats non-brown. If you have blue eyes, you had to have inherited a recessive, non-brown eye allele from both parents. 
This is a case of a dominant allele masking the expression of a recessive allele. Recessive alleles are only expressed if you inherit two of them, one from each parent.

For example, if your mother has brown eyes and your father has blue eyes (non-brown), you may have ended up with brown eyes. Your father's blue eyes are a recessive trait, and although you have an allele for blue eyes, the dark eye allele 
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