Parents who have more than one child are able to compare varying personalities despite a similar upbringing. Understanding the fundamentals of what builds a child’s personality requires one to revisit the inexhaustible argument of nature versus nurture. Most twin studies have come to the conclusion that it is a combination of both, and in that case, siblings would only provide a smaller impression on overall upbringing. Everything, however, is circumstantial when it comes to how much of an effect a brother, sister, or lack thereof, has on an individual.