Are you a laid-back person or an ambitious one? Are you spontaneous or more of a control freak? Whatever your responses to these questions, most of us feel the answers are pretty fixed. Through experience, will, or perhaps with a great deal of therapy, you might be able to shift your character slightly. But we're basically stuck with the personality we developed as kids.

That might be the common view (and one that was no doubt reinforced around many holiday tables last week as adult children were reminded by relatives that old labels are hard to shake) but according to psychology, it's at least partly wrong. And that matters not only for avoiding fights with your siblings at the holidays but also for your business. How? Those that surround us and the roles we take on can actually have vast effects on our personality, and our personalities have vast effects on our business.

If you're still unsure about the proposition that personality is flexible, perhaps this quick account of a classic psychology experiment called "The Effects of Changes in Roles on the Attitudes of Role Occupants" will convince you. In the experiment, union workers were promoted to foremen and psychologists watched as their beliefs grew rapidly and significantly more pro-management and anti-union. When some of them went back to the rank and file, their anti-management sentiments returned. The infamous Stanford prison experiment is an even more extreme illustration of the malleability of our personality and beliefs.

As motivational speaker James Rohn succinctly put it: "You are the average of the five people you spend the most time with." Rohn may be oversimplifying, but it's hard to deny that spending time with irritable complainers, for example, pushes us towards moaning, or that those exposed to daily risk-taking or ethical lapses can become more accepting of these behaviors. Which is why you should consider carefully the company you keep, according to a recent post on Men With Pens.

Using the Rohn quote as a jumping-off point, writer Annika Martins notes how much time business owners spend trying to cultivate the ideal "tribe" of customers and how little thought they often give to the "foundational tribe" of people that actually surround them every day and have huge effects on their psychology. She writes:

Most of us spend a lot of time thinking about and cultivating our ideal business tribe, but hardly any time creating our best possible foundational tribe. Why is that?

We need a strong foundational tribe in order to be able to create an awesome business tribe. It's basic common sense: if you feel alone and unsupported, all of your endeavors, business and otherwise, are going to be a heck of a lot harder. Our foundational tribe is the engine that drives us to run our business, complete the marathon, publish that book or take that vacation. Pretty important tribe, huh?

So ask yourself this: when you think of the average of the five people you spend the most time with, are you happy with that idea? Or do the names you come up with disturb you a little?

Maybe it's time for some tribe cleaning.

Martins concedes that cleaning up your social circle to create a better foundation for your business isn't easy, "especially when we have history with the person, mutual friends or maybe even live on the same street," but she urges those who are serious about have the strength and stamina to build their businesses think about ensuring they have the best tribe supporting (and molding) them in the new year. Do you have any associates that you need to kick of the island of your personal tribe for the sake of your mental health?