Having Hair On The Back Of The Hands Is A Dominant Trait

Having hair on the back of the hands is a dominant trait. If two people

Having hair on the back of the hands is a dominant trait. If two heterozygous individuals have children, the probability that they will have a child without hair on the back of their hands is 25%. This is because when two heterozygous parents (Hh) are crossed, the punnett square yields a genotypic ratio of 1 HH : 2 Hh : 1 hh. Only the homozygous recessive genotype (hh) results in a child who does not have hair on the back of the hands. Therefore, the chance is 1 out of 4, which equates to 25%.

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The inheritance of physical traits in humans often follows classic Mendelian patterns, with dominant and recessive alleles influencing phenotype. The trait of hair on the back of the hands is a classic example of a dominant trait. When examining the probability of offspring inheriting or not inheriting a trait, Punnett squares provide a clear visual and computational method to determine chance outcomes based on parental genotypes.

In this specific case, both parents are heterozygous carriers (Hh) for the trait, meaning they possess one dominant allele (H) and one recessive allele (h). The dominant allele (H) results in the phenotypic expression of hair on the back of the hands, while the recessive allele (h) does not. Crossing two heterozygous individuals (Hh x Hh) produces the following genotypic ratio: 25% HH, 50% Hh, and 25% hh. Among these, only the hh genotype does not express the trait, meaning children with the hh genotype will lack hair on the back of their hands.

Therefore, the probability of having a child who does not exhibit this trait—that is, a child who is homozygous recessive (hh)—is 25%. This is equivalent to a probability of 1/4 or 25%, aligning with classical Mendelian inheritance patterns where the recessive phenotype appears in a quarter of the offspring of two heterozygous carriers.

This example underscores how simple genetic crosses can predict trait inheritance probabilities in humans and highlights the importance of understanding the underlying genetic mechanisms and how they translate into observable traits.

Furthermore, understanding such genetic principles is crucial in fields ranging from medicine to evolutionary biology, as it helps predict inheritance of genetic disorders, understand variability in populations, and inform genetic counseling efforts.

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