This is a very hotly debated subject. As the title of this thread suggests, many people believe this behavior is "instinctual", and therefore can not be changed. The problem with this is that "instinct" is
not a fixed and never changing behavior. Instinct is a term used to separate human behavior from animal behavior. When a primate, or any animal (other than us) nurses, cleans, protects, and generally cares for its young, we call it "instinct". When a human mother does the
exact same thing, well.... It's just part of being human. Instinct is also used to describe behavior that we simply don't understand. How does a monarch butterfly migrate from Central America to Canada over several generations? Well it's instinct of course.

All behavior is influenced by environment. It doesn't matter if we call the behavior "instinct" or not. We can not take a wild animal, completely alter its environment, and expect it to behave exactly as it would in the wild. Even if we call the behavior "instinct". Nature simply does not work that way.
Wild clowns start life, in the egg, at the base of their host anemone. For about the first week, the father fans the eggs, bathing the developing little ones in substances produced by their host anemone. When they hatch, they emerge into a world dominated by substances produced by their host anemone. Then they drift away and eventually go through metamorphoses. At this point, they use these same chemical cues, from their host anemone, to guide them home. They then spend the rest of their lives within the security of their host anemone. Until they are captured for the trade, that is.
Most captive bred clowns have been denied exposure to these substances during crucial developmental stages of life. Then they spend several months in "grow out" tanks where development continues without exposure to their host anemone. IMHO, it would be unrealistic to expect two animals with such vastly different environmental influences, especially during development, to have the exact same behavioral patterns. This would be like expecting someone born and raised in a small village in the Amazon to behave exactly like someone born and raised in New York City. It's simply not going to happen.
I do believe that captive bred clowns will move into their natural host, in time, if it is provided. I just don't believe they have the same sense of urgency to do so, as a clown that has spent its entire life (minus roughly one week) in the security of its natural host. Every wild clown I've dealt with would go into its natural host almost immediately. My LFS added a pair of Picasso's to their display tank with two magnificas. It was two or three weeks before one of them moved into the anemone. I can not believe this would have taken so long if the clowns were wild.