The practice of inbreeding isn’t just bad for your family gene pool. It’s bad for creative teams as well.

The same genes getting mixed over and over again makes for messed-up people – and messed-up ideas.

One of the more famous examples of inbreeding was the House of Habsburg, the throne of the Holy Roman Empire. There was so much inbreeding over six centuries that the bloodline developed a jaw deformity so pronounced that the last of the Habsburgs, Charles II of Spain, could not even chew his food.

Which is not to say that if you don’t bring start bringing new people into the creative fold, you won’t be able to chew that turkey wrap you’re having for lunch. However, generating ideas with the same small group in isolation over and over and over again, without exposure to new personalities, produces ideas that get weaker and weaker, and uglier and uglier over time.

Revolutionary breakthroughs are often conceived by people new to the process, literal rookies or strangers to a project.

Fancy-schmancy business experts call the practice of introducing new blood “horizontal sharing.”

Basically, being an outsider is good. Outsiders bring different expertise from different disciplines. They see things differently. They aren’t stuck on the same things you are. They have objectivity.

Recent research from The Kellogg School of Management revealed that the most effective creative groups tend to be a mix of well-acquainted members and outsiders.

Researchers found that Broadway musicals were ideal venues to study collaborative creative dynamics because they require the collective effort of so many different types of people, generally a composer, a lyricist, a librettist who writes the plot and dialogue, a choreographer, a director and a producer.

Their study sampled 2,092 people who worked on 474 musicals from 1945 to 1989.

If a musical were developed by a team that had worked together several times before, you would expect this “incumbent team” to be the most successful, since they were more familiar with one another as collaborators. However, this was not the case. Financially successful and critically acclaimed musicals were more likely the result of new people being brought into the fold.

The most successful teams were the ones where some collaborators knew one another quite well but were joined by a moderate amount of new and unfamiliar talent. A mix of relationships and experiences meant that the artists could interact efficiently while managing to incorporate new and different thinking.

In contrast, working in small groups with the same people over and over again can undermine innovation due to a decrease in artists’ ability to think outside of themselves and break convention.

The researchers extended their studies into science publishing (psychology, economics, ecology and astronomy). They found exactly the same thing. Breakthroughs came from adding new people.

Introducing outsiders inspires new combinations of thinking. And reduces your chance of jaw deformity.