As it turns out, part of the inclination to engage in brokerage behaviour is personality-related. There is a classic psychological scale with which one can measure a pre-disposition of an individual to change/adapt his or her behaviour to the situation in a chameleon like fashion–this scale is called “self-monitoring”. If you want to take a self-monitoring test, here is a link to do that, you will find out to what extent you are chameleon like in dealing with people:

http://pubpages.unh.edu/~ckb/SELFMON2.html

High self monitors are more likely to build open networks (i.e. become brokers) than low self monitors. Because high self-monitors often tell people what they want to hear (and behave the way they think people want them to behave), these individuals are initially quite likable by the others. At the same time, these individuals are also strategic in building their networks to become brokers in them. This is what a recent study in the Administrative Science Quarterly has found.

http://asq.sagepub.com/content/55/4/639.short

If you are high self monitor, chances are you are also likely to be a broker in your workplace network and get all the benefits from it.   If you are low self monitor, beware of your friends, some of them might be high self monitor brokers who absorb your knowledge, recombine it with the knowledge of the others and benefit from it. What should you do? If you are a low self monitor, then you need to make an extra effort to meet new people from different departments, different work groups, etc. who are not likely to know the same things as the people you usually hang around with. In this case, you will increase the “openness” in your network and hopefully get some brokerage benefits out of it.

Good luck!