Jenniskens believes that this object may not, in fact, be an asteroid. “This is a now-dormant comet nucleus, a fragment of a bigger object that, after breaking up in the not-so-distant past, may have caused the gamma Piscid shower of slow meteors (IAU #236) that is active in mid-October and early November,” he says.
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he says.. :-)
How the heck do you know what came from where in the first place?
A very cool profession, in more ways than one.
They run the orbits backwards. Gravitationally forced dynamics works as well with time running backwards as forwards. Then when two, or usually more, objects "come together" in reversed time, they rule that a either a collision or at least a strong gravitational interaction, which change orbits. They have to take into account the gravity of the Sun and the planets. Although they could ignore most all but Jupiter most of the time, unless the object gets "close" to some other object. Where "close" depends on the size of the other object.
Some of the people who do this work for a different division of my employer. See 'em on National Geographic, History Channel, etc, all the time.