via our egghead friends at Astrobiology Magazine, a nice feature on the origins of our solar system, and they are thought to be violent. The question being raised?
"We know that our solar system has at least one planet with life – Earth. So perhaps solar systems that formed in ways similar to our own will also have the potential for life. But this invites the question: how normal was the formation of our solar system?"
Short Answer: Not very.
Long answer: Stars form in clusters of hundreds to thousands from large gaseous clouds of matter. However, star formation form such clouds is not easy. Gravity has to overcome the outward pressure from the heat such gas cloud formations posses, which only happens very rarely. The reason it happens at all is turbulence within the cloud causes an eddy, which will sometimes create a cloudlet that eventually forms into a star. The turbulence itself is thought to often come about from external factors, such as supernovae.
There is a growing body of evidence that our young solar system may have experienced such supernovae inspired tubulence, perhaps many such. Due to the percentage of trace elements found in solar sytem meteorites, it is thought that our Sun formed in a huge stellar nursery, with perhaps hundreds of thousands of stars. What impact that may have had on the orgins of life is a subject of much debate in the scientific community, but it certainly had an impact of what types of heavy elements are found on our planet. Such turbulence in the solar system's origins might also help explain the impact thought to have created the unusual Earth-Moon system we enjoy today as well.