Answer :
Final answer:
People physically differ mainly due to differences in their alleles, which are variations of genes. Environmental factors also play a role in how these traits are expressed. Ultimately, both genetics and environment contribute to the distinct characteristics seen among individuals.
Explanation:
Why People Differ Physically
People differ physically from one another primarily because their alleles differ. Alleles are different versions of a gene that arise due to mutations in DNA sequences. For instance, consider the gene that determines blood type, where the alleles can be A, B, or O. An individual's blood type, which is a trait, results from the combination of alleles inherited from each parent (for example, OO or AB).
Moreover, physical differences can also be influenced by different environments. For example, an individual frequently exposed to sunlight may develop darker skin to protect against UV rays. Thus, while environment plays a role in the expression of traits, it is the variation in alleles that primarily accounts for genetic differences among individuals.
In summary, genetic variation is essential in explaining why people exhibit different physical characteristics. Each person's unique genotype, comprised of various alleles, interacts with environmental factors to shape their phenotype, leading to the diversity we observe in human populations.
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