Love this word! I use it regularly, and never hear it enough. Whenever I do hear it used (not by me), it always makes me smile.
Penchant comes from the French "pencher" for bend or incline from the Latin "pendere" for "to hang or weigh" as devolved through the Latin "pendicare" for "to lean". So as the pendulum or pendant (both of the same origin) hangs and perhaps sways in a direction, perhaps from a perceived imbalance, a movement whether deliberate or by the earth's rotation or magnetism, or an architectural anomaly, the bob appears to "incline" towards something. Of course, like all good words related to the movement of objects, it was immediately applied to people where it stuck and the object origin was abandoned. Thus, penchant not only means the emotional inclination toward a person or idea, but a strong such inclination, as if the original "inclining" were due solely to magnetism causing an unnatural attraction of the pendant to the other object.
She has a penchant for exploring new blog sites. His penchant for forensic accounting made him a formidable business executive. Her cat's penchant for moist cat treats was guaranteed to bring the pet out of hiding just from rusting the bag. As an initial note, penchant is nearly always used with the preposition "for", which makes this practically a phrase, and it can be used with any sentient creature which could have a preferential liking of something without issue. Now, the old IBM 386's had a penchant for crashing just before the user tried to save. Possibly, if you think outdated computers like to foil user's reasonable efforts, and give such intent to the computer. Derelict buildings have a penchant for drawing crime. Probably not, even if one were being sarcastic. There's just nothing cognitive about a building that it could even be remotely analogized to a person. Vague political theories have a penchant for being bandied about by the uninformed. Again probably not, because the theories are not the ones with the liking that is causing anything. Politicians have a penchant for bandying about vague political theories. Correct. And of course, she has a keen penchant for picking on plaintiffs' counsel.