Today I Heard My First . . . . .
ChatterBank1 min ago
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For more on marking an answer as the "Best Answer", please visit our FAQ.Every aspect of what each human looks like (and in part thinks) is controlled via DNA. It's all to do with the combination of five base elements. (ATUCG) The combinations of these (though only four are used as U is a sign of molecular degradation) in long strings is what defines everything about us.
So simply, a string of these chemicals will be the direct reason someone has blue eyes, while their sister may have a slight variation which may give her brown eyes. It is also why we 'inherit' aspects of our parents and sometimes their parents. The DNA sequences can be carried over from one generation to the next... (DNA is often referred to as a molecule of heredity.)