The U.S. Constitutionâs 10th Amendment is arguably the most important of all the amendments in the brilliant document that helped shape the United States.
Not even identical twins have the same DNA--although theirs would be far closer than anyone else's. DNA changes over time. Odds of two siblings having the same DNA who did not split from the same zygote are vanishingly small.
Because you have two copies of your DNA (one from Mom and one from Dad), you might end up with two different alleles of the same gene. In that case, we would say you are heterozygous. The opposite of that is homozygous, two identical alleles.