I believe that EVERYONE has the capability to be "wired" for Poly... Just like I believe that everyone has the capability to be "wired" for bisexuality.
Think of a person's sexual compatibility (both number of partners and gender of partners) like a hallway that stretches on forever, with doors on both sides. One side is "male doors", the other side is "female doors"...
In a poly/bisexual, all the doors are open and the person can freely and happily walk through any and every door at any time.
In a poly/monosexual (hetero OR homo), all the doors on ONE SIDE are open and the person can freely and happily walk through any and every open (on the side that IS open) door at any time.
In a monogamous/bisexual, all the doors can be opened, but only one can open at a time.
In a monogamous/monosexual (hetero OR homo), all the doors on ONE SIDE can be opened, but only one at a time.
In all cases, the hallway and doors are still there... just not in all cases can they all be passed through.
Also, in some cases, during our indoctrination while growing up, some of those doors of ours may be wedged shut by well meaning, but ignorant parents... and it may take us a while to "un-wedge" them... and some people that otherwise would have been poly, or bi, or both (and would undoubtedly be happier being that way) may not ever get their doors "un-wedged".
I hope that makes sense. It was much easier to picture in my head than it was to type it out
ETA: Oh, and as to how it compares to cheating... Cheating is just a lack of honor and integrity. People can lack honor and integrity in/about any subject.