Thank you for your question. If we assume the facts of the question as true, the question presupposes that volume equals importance. If the 2% difference gives rise to very distinct and important differences then monkeys and humans are not the same, as is clear from the difference in the way monkeys and humans live in this world. Another assumption is that all that is involved in being human is contained in DNA, and not just a human's physical aspects, which is something that is not established.
May you always be successful