Question

What are some of the dominant and recessive traits in human beings?

Answer 1

Hint: Recessive traits are the traits that are only expressed when the progeny contains two copies of the recessive allele. A recessive trait is always homozygous ‘aa’. Dominant traits are the traits that are always expressed in the progeny when the dominant allele is present in either one or two copies. A dominant trait can be homozygous or heterozygous ‘AA’ or ‘Aa’.

Complete step by step answer: Some common examples of the dominant and recessive traits in human beings are listed in the table below:

Dominant traits	Recessive traits
A/B type blood group	O type blood group
Ample body hair	Little to no body hair
Astigmatism	Normal vision
Male baldness	Not bald
Broad lips	Thin lips
Broad nose	Narrow nose
Dwarfism	Normal growth
Hazel eyes or green eyes	Blue eyes or grey eyes
High blood pressure	Normal blood pressure
Large eyes	Small eyes
Migraine	Normal
Mongolian Fold	No fold in eyes
Near-sightedness	Normal vision
Rh factor (+)	No factor (Rh-)
Second toe longest	First or big toe longest
Short stature	Tall stature
Six fingers	Five fingers normal
Webbed fingers	Normal fingers
Tone deafness	Normal tone hearing
White hairstreak	Normal hair colouring

Additional information: Other examples of dominant traits include freckles, cleft chin and dimples. Almond-shaped eyes are dominant over round-shaped eyes. This feature is controlled by recessive alleles. Detached earlobes dominant over attached earlobes and right-handedness are dominant over left-handedness.

Note: Some traits are linked with sex chromosomes, especially X chromosome. These alleles are inherited along with the X chromosome from the mother in case of a boy or from either mother or father in case of a girl. Females contain two X chromosomes (XX) and males contain one X and one Y chromosome (XY). An example of sex-linked genes is the genetically inherited disease haemophilia.