But this "syndrome," and many other negative stereotypes regarding birth order, isn't exactly backed by the best science, and middle kids often aren't as bitter and resentful as Jan Brady would have you believe.
In fact, plenty of successful people known for their leadership and influence - Bill Gates, Nelson Mandela, Warren Buffett, Abraham Lincoln - were middle children.
Dr. Catherine Salmon, author of "The Secret Power of Middle Children," even posits that middle kids are best poised for success because they had to be better at negotiating the peace, were able to take more risks because less attention was on them, and are used to working hard for their accomplishments.
Patty Stonesifer, founding CEO of the Bill & Melinda Gates Foundation and now chief executive of Martha's Table, a provider of food and clothing for low-income people, would argue there's something to this theory.
In an interview with the New York Times' Adam Bryant, Stonesifer, the sixth of nine children, attributes her success to her birth order.
"Being in the middle taught me to use my voice," she explains. "I was a talkative child, I had a lot to say, and I knew how to get my points across at an early age because there were a lot of people with a lot to say at the table."
"Being right in the middle also teaches you that it's not about you," she adds. "Some of my first memories were folding diapers for my younger siblings or taking somebody's hand to go to school. It was always about making sure that the whole came together."
This attitude helped Stonesifer move up the ladder pretty quickly early in her career at Microsoft. She recalls an annual managers' retreat where she questioned the executive team (including Bill Gates) about where Microsoft was heading. "I literally was packing my bags within a few weeks after the retreat to run our operations in Canada," she says.
"The thing about growing up at a big dinner table is that people are going to disagree and people are going to have points of view, and for me, that was very comfortable," Stonesifer tells Bryant. "I'm really comfortable with a fair amount of conflict and disagreement. As long as people are nice and not mean about it, those conflicts can be really productive."