Interesting topic! My son is tube-fed due to protein intolerance. We suspect that he has also associated food with pain and has never really "learned" how to eat properly. He has become very orally aversive. It's a mixed blessing. On one hand, he has the simplicity of only having to mix up the formula and putting it into the pump bag. (Hardly any dishes dirtied!) On the other hand, it's an uphill battle in working with an OT to get him to even enjoy other mouth activities, like blowing bubbles and using musical instruments.
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Apathy is a dominant gene. Mutate.