Dominant and Recessive Traits of man

Earlobes

An attached earlobe is one that attaches directly to the head. This trait is recessive. A free or unattached earlobe has a fleshy part that hangs down just before the point of attachment.

Gene symbols: F= gene for free or unattached earlobes.

f= gene for attached earlobes.

Little Finger (Pinky)

This trait is characterized by a shortened middle bone of the fifth finger. Because of the triangular shape of the imperfect middle segment, the end bone of the little finger curves in toward the fourth finger. This is a dominant trait.

Presence or absence of the trait can be determined by placing the slightly spread fingers on a flat surface and noting the alignment of the fifth finger in relation to the other four. Those with the condition will notice a slight angling of the fifth finger toward the other digits.

Gene Symbols: B=gene for bent little finger

b=gene for straight little finger

Ear Point

The presence of a conspicuous point or a bump of cartilage on the outer rim of the ear is inherited as a dominant trait. This dominant gene shows variable expression. Some individuals have a Darwin’s point on only one ear. Some individuals transmit the dominant gene, but show the recessive phenotype.

Gene symbols: P= gene for Darwin’s point

p= gene for no Darwin’s point.

Ear wiggling

The ability to wiggle your ears without touching them is probably dominantly inherited.

Gene Symbols: E= gene for ear wiggling

e= gene for no ear wiggling

https://www.youtube.com/watch?v=RCEmmM8I4MQ

Eye Dominance

In this trait one eye is favored over the other. About 97% of people have this condition

which is probably dominantly inherited. About 65% show right eye preference.

Use the following procedure to determine whether you have a dominant eye and, if you do, which eye is dominant. Find a small object at least ten feet away. Close your right eye and point to the object. Hold your hand steady and then open both eyes. Are you still pointing at the object? Repeat this procedure with your left eye. If after testing both eyes, in both cases you were still pointing at the object you do NOT have a dominant eye. If only one eye left you still pointing at the object then that eye is your DOMINANT one.

Gene symbols: O= gene for eye dominance

o= gene for no eye dominance.

http://www.youtube.com/watch?v=UVWEQk1JSl4

Photic Sneeze Reflex (achoo syndrome)

This trait is characterized by sneezing just after stepping out in to direct sunlight. It is found in about 1/3 of the population.

Gene Symbols: A= gene for photic sneeze reflex

a= gene no photic sneeze reflex

https://www.youtube.com/watch?v=MfwszszF1wY

Facial dimples

The occurrence of natural indentations at the corners of the mouth or on the chin (dimples) is controlled by a dominant gene. Facial dimples may be inherited as an irregular dominant trait. A dimple is a slight depression or dent in the surface of the human body, caused by adherence of the skin to deeper tissues. Dimples appear most frequently on cheek or chin.

Gene Symbols: D= gene for dimples

d= gene for no dimples

Hitchhikers thumb (distal hyperextensibility of the thumb)

This trait is characterized by the ability to bend at least one thumb backward 60⁰ or more. This trait is recessive. Considerable variation exists in the expression of this gene. One in twenty who carries the gene will not express the characteristic. The frequency of the trait in the US population is 0.496.

Gene Symbols: N= gene for straight thumb

n= gene for hitchhikers thumb

Interlocking thumbs

When the fingers are interlocked, some people place the left thumb on top of the right and others with place right over left. Studies of pedigrees indicate that the placing of the left over the right is due to a dominant gene, while the right thumb on top is do to a recessive gene.

Gene Symbols: T= gene for left thumb over right

t= gene for right thumb over left

Median Upper Diastema (gap between front teeth.)

This is the presence of a conspicuous gap between the central upper teeth (middle incisors). usually a little piece of gum extends down between the teeth where there is diastema. this tray is thought to be a dominant trait. If you had this trait before orthodontic work be sure to indicate that you had (have) The trait.Gene symbols: G= Gene for gap between front teeth

g= Gene for no gap between front teeth

Long Palmar Muscle

This trait is characterized by the presence of a third palmar muscle. The presence of the muscle can be detected by examining the tendons which run over the inside of the wrists. to see the tendons clearly, clench your fists tightly and flex your hand (that is, bring it toward the side of your wrist). observed Orefield attendance. If there are three, you have the long palmar muscle. The gene for long I'm palmar muscle is recessive. both address should be examined, because the trait is sometimes present in one wrist and not the other because of variations in the expression of the gene. The trait is not present in either wrist, you have the dominant gene.

Gene Symbols: M= gene for not long palmar muscle

m= gene for long palmar muscle.

Middigital Hair (Midphalangel Hair)

The presence of hair in the middle section of the finger is a dominant condition. Those lacking the trait are homozygous recessive for the trait. you may require a hand lens to determine your phenotype, since the presence of even the slightest amount of hair qualifies as the dominant condition. complete absence of hair is a recessive trait (m). multiple alleles for the presence of the hair exists so that the hair may appear on only one digit (M1) or all digits (M4)

Gene Symbols: M= gene for long middigital hair.

m= gene for not middigital hair.

Pointers Thumb

The ability to “cock” the thumb at a right angle is a dominant trait

Gene Symbols: P= gene for the pointer’s thumb

p= gene for “normal” thumb

Pigmented Iris

The total absence of pigment in the outer layer of the iris results in individuals who are blue or grey-eyed. Lack of pigment is inherited as a recessive trait.

Gene Symbols: I= Gene for dark eyes

i= Gene for blue or grey eyes

Widows peak

Widows peak is a distinct downward point of the frontal hairline. The trait is dominant in humans. Homozygous recessive individuals possess a straight hair line. The trait is expressed in varying the degrees.

Gene symbols: W= Gene for widows peak

w= gene for no widows peak

Short big toe

The relative lengths of the hallux (big toe) and the second toe appear to be controlled by a single gene pair. A big toe longer than the second toe is the recessive trait. The dominant gene results in a short big toe in relation to the second toe. rarely, the phenotype may defer on each foot. if one or both big toes are either equal to or greater in length than the second toe, the recessive gene is present.

gene symbols: S= gene for short big toe

s= gene for long big toe

Tounge folding

This trait involves the ability to fold the tongue backward, without pressing it against the upper teeth. It is very rare, occurring in the human population at a frequency of less than 1 per thousand. This trait is thought to be a dominant trait.

Gene symbols: F= gene for folding tongue

f= gene for non-folding tongue

Tounge rolling

This trait is characterized by the ability to roll the tongue upward from the sides. the roller phenotype is dominant. Individuals unable to do this are homozygous recessive for the trait. The frequency of tongue-rolling in the US is 0.65.

Gene symbols: R= gene for tongue rollingr= gene for non-tongue rolling