Question

In humans, the gene for curly hair (H) is incompletely dominant to the gene for straight hair (h). Individuals that are heterozygous (Hh) have wavy hair. Two wavy-haired heterozygous parents have a child. What is the likeliness that the child will have wavy hair?

Answer 1

Answer:

1/2 (50%) of the offspring will have wavy-hair

Explanation:

The question is describing a autosomal type of inheritance pattern, being the dominant trait curly hair (allele H), and the recessive (non-dominant) trait straight hair (allele h). There are three phenotypes one can obtain from this allele: HH ⇒ Curly hair, Hh ⇒ Wavy hair, and hh ⇒straight hair. We are informed that two wavy-haired heterozygous parents have a child, meaning that both parents present a genotype of Hh. To obtain the probability of type of offspring, it is necessary to perform a Punnet square:

             H      |      h

———————————

H    |     HH     |    Hh      

———————————

h    |     Hh       |   hh    

One can conclude that the amount of offspring with wavy-hair phenotype, will be 2/4 = 1/2 = 50%