The thumb gene also known as the hitchhiker's thumb or bendy thumb is detected by the phenotype of a person. The phenotype is responsible for the physical appearance of people. Dominant and recessive traits comprise of alleles that help in the composition of chromosomes.
Traits that manifest strongly are known as the dominant traits and they are responsible for the straight thumbs found in some individuals. The recessive alleles manifest themselves when the dominant traits are not expressed. This would thus give rise to the bended thumb.
