Parents often have a clear set of expectations for the first child, while middleborns are left to their own devices. That lack of expectations is often thought to foster an underachieving mindset, but that's not always the case, Salmon told Business Insider.
In fact, having the freedom to choose their own path in life can result in a successful career. It just will likely look a bit different than that of the parents or siblings.
Being in the middle can allow children to develop skills that others don't have to practice until later in life, like negotiating for peace between siblings, figuring out what people want, being independent, and trying new things, Salmon said.
"It can create certain kinds of people, like Bill Gates, Carly Fiorina, and Charles Darwin — people who are willing to entertain things that are outside the box," Salmon said.