Question

1. Is anyone dominant for every trait? Is anyone recessive for every trait? If not, what does this show about dominance and recessiveness of traits in people?

2. If a man is homozygous for Hitchhiker’s thumb and marries a woman with homozygous dominant alleles, what is the probability of them having children with Hitchhiker’s thumb?

3. Two people that look alike have thousands of common traits. How often do you think that genetic twins (aside from identical twins) exist? Explain your answer.

Answer 1

Ans 1) there are thousands of genes present in the body and there are two alleles for each of the gene. However, it is not possible that each gene in an individual have only dominant or only recessive trait. It is very rare in case it is possible that all genes are either homozygous dominant or recessive. The dominant traits are those traits which are visible and expressed while recessive ones are those that are not expressed but silently expressed.

Ans 2) In this the probability will be 50% heterozygous and 50% will be homozygous recessive. It is because the alleles can pass from the man or woman to the child and the probability of passage is around 50% for both.

Ans 3) The only case when there is likelihood for the genetic twins to exist is in terms of clones. Otherwise there is never 100% identical genetic twins and the chances are very very less.