The first level of organization are living cells
Protein, the building blocks of proteins are amino acids, different sequences and combinations of these amino acids result in huge numbers of proteins which have a variety of functions.
Its is possible because your previous family members like grandparents can have dimples special features like eye color can skip a generation so for example my family all have brown eyes and my mom previously had twins with blue eyes but my great grandma has blue eyes a feature skipped from my family and she got it from my elders
