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.
Either two individuals can or they cannot be siblings, or parent and child. There is no in-between (but there can be on a DNA test, but that is a fault with the test and not with the relationship between those two individuals). In our case it is the probability of the event of two individuals being siblings.