Some dominant and recessive traits in humans

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.

Learn about Dimples, Eye Color & Tongue Rolling

10 Human Genetic Traits of Simple Inheritance

​Page last updated: 10/2017

Some Genes Mask the Expression of Other Genes

In some instances, the allele that you get from one parent may block the expression of the allele you received from the other parent. 

Girl with cleft chin, dimples and blue eyes (no melanin).

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. Your genotype (DNA) determines the actual traits that you have (called the phenotype); such as eye color, nearsightedness, and whether or not you have dimples.

Simple Inheritance Traits of Complete Dominance

This article explains the inheritance of several genetic traits, including: 

plus provides a printable heredity assignment based on this article, for students to complete. Forward this article to family members so they can do the same. Then compare notes. For some traits, you'll be able to trace the inheritance pattern of the associated genes through your family. Have fun!

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).

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 that you received from your mother masks the expression of the blue eye, recessive allele. 

1. Achoo Syndrome: This dominant trait is also called the photo sneeze reflex. If, when suddenly exposed to light, you sneeze (usually two or three times) you have the genes for achoo syndrome. Next time you go to a movie, exit the dark theater through a door that leads directly outside. It's fun to wait outside and watch the people emerge from the movie. Some will sneeze as soon as they are exposed to light.

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

2. Chin Cleft: A prominent cleft in the chin is due to the structure that underlies the Y-shaped fissure of the chin. This is due to incomplete fusion of the left and right halves of the jaw bone and muscle. Females appear to be less conspicuously affected than males.

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

​3. Early Onset Myopia (Childhood Nearsightedness): Nearsightedness, or myopia, is a complex trait with at least 4 gene loci involved, however the heritability of myopia is very high and shows a dominant pattern.

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

4. Bent Little Finger: A dominant allele causes the last joint of the little finger to dramatically bend inward toward the 4th finger. Lay both hands flat on a table relax your muscles, and note whether your have a bent or straight little finger.

Recessive (don't have it) ___.

Father and son who both have bent little finger. Mother (not pictured) does not have this trait.

Genetics Practice Test Questions

SPO offers Sample Science Test Questions on many different science topics. Below are links to those that relate to genetics.

What are some dominant traits in humans?

What are some recessive traits in humans?

What are 5 examples of recessive traits?

What are 10 examples of inherited traits?