The genes coding for a common body design is similar in all humans, hence all offsprings inherit the same body design. However, every human differs from the next in certain genes. This gives us the differences in features.
Variations appear in progeny of sexually reproducing organisms due to random separation and coming together of chromosomes during gamete formation and gamete fusion, crossing over and mutations. This leads to the subtle changes produced in the offsprings from the parents.
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