EC - while I can understand your thoughts about altering an animals behavior through a wildly different method of being raised, then how could this explain stocked fish? Each year, thousands (if not millions) of captive raised fish (salmon, trout, bass, northern, panfish, musky, the list goes on) are raised by the Fish and Wildlife department and released into the streams and rivers around the country. There is a portion of die-off (expected since the entire batch is raised to a size where in the wild many would have been picked off by predators), but there is no arguing the effectiveness of the stocking program. If the origins of each fish mattered, the program would not work, as the behavior of the released fish would be altered to a state where they would not live and procreate in the wild (not seeking out shelter, waiting for food to be fed rather than catching their own, not knowing where/how to spawn).
IME, I have never had difficulties with getting a CB fish to accept a natural host either. If it truly is an instinctual and not a learned trait, then it cannot matter where the fish is born/raised. I think most agree that an clownfish taking on an anemone is an instinctual matter (hence why natural fish/nem combos are important - if it were learned the likelihood is higher they would accept any anemone much the way they will host any sort of inanimate object in the tank). Furthermore, fish have not been proven to have a thought logical based thought process capable of thinking and reasoning. They are instinctual animals which respond to external stimuli the way their genetics have coded them. If it were a learned trait, there should be a much clearer delineation between CB and wild fish with accepting host nems, not the much more skewed dataset as shown above. There are well respected people who have experienced both sides. I would argue, that if the origins did make a difference, you could put a clownfish in a tank with a natural host, and from the interactions be able to tell if it were wild or CB. I've never heard of anyone being able to do this. I sometimes wonder if those who seem to have experienced "CB clownfish not taking to nems like wild ones" are putting a unintentional biased to their observations. If I test drive five red cars that are all much faster than the blue cars, I could conclude that red cars are faster than blue - meanwhile skipping over the fact that all the red cars were Corvette's and the blue cars were Pinto's.
It is a tricky thing attempting to match observations with causes - especially when dealing with animals that each can have their own individual personality. It makes establishing cause/effect relationships very difficult. In this case, however, I very much do believe there exists a lack of clear evidence to support the claim that a wild caught clownfish will take a host nem much more readily than a CB fish.
(One experience - A three month old Clarkii. Once acclimated, I released if from my hand into the tank. Literally the first movement it made was directly into a nearby RBTA. Raised in a breeder tank, released into a full reef, and the nem was it's first choice of home. Granted it could be a coincidence, but it would support evidence to disprove the null hypothesis that a wild fish takes a host quicker).