Can you give me guidance for dealing with my friend who is a very picky eater?

I have a very good, close friend that I’ve known for more than 2 years. We have grown close in that time, because we have a lot in common.

He is a very picky eater. He is also very vocal about it. He will often make comments about food that he won’t eat. I usually counter it by making noises showing my pleasure at anticipating the good food.

He is very knowledgeable about food and is a good cook. He can often name the ingredients of dishes.

Some of his dislikes baffle me. He hates butter, for instance. I can’t even fathom that.

I have several questions.

1. What makes someone a picky eater? Is there a cause?
2. Is this something that I should talk about with him? He acts like his picky eating is something to be proud of, but in my experience, it belies a lack of maturity or perhaps just a lack of adventurousness.
3. When he comes over for dinner, should I take his tastes into my plans for what I’m preparing?

I understand having likes and dislikes. This is not that. This is deeper.

GENERAL SECTION QUESTION