I have been trying to avoid posting on this as the OP made me rather cross but can't resist!
I was a fussy eater. Edam's early post about tonsillitis is interesting as I also suffered from this as a child....
But I think one of the main factors in my case was that I just did not like a lot of the food I was being given. My mother was not a great cook, she had a lot of demands on her time (looking after elderly relatives) and producing a delicious meal by 1pm (which was when we had our main meal) was probably unrealistic. A lot of our meals consisted of meat, under-cooked potatoes (the time factor) and over-cooked vegetables. The concept of gravy or a sauce was alien to her.
To answer the person who asked if fussy eaters were tolerated in large families - ours was large and yes, eventually my mother stopped trying to force us to eat what the adults were having. I would think she often produced 3 different dinners.
I improved dramatically when I left home!
The reason I no longer class myself as a fussy eater is that I enjoy a wide variety of food, but to this day I would not choose to eat that sort of meal. I prefer casseroles, pasta, curries, etc (anything with a bit of flavour, basically). I do wonder if when some people claim their children are not fussy it is because they only give them food they like?!
I can remember feeling like I would throw up when forced to try something I hated. Funnily enough, my fussiness was mainly about dinners. I happily ate soup, salads, fruit, etc.
Probably because of my own experience I hate to see a parent trying to force a child to eat something. Had this recently when relatives were staying with us and maybe felt they "had" to be firm in front of us.
I have one good eater and two fussies. I will admit that the thought has crossed my mind that maybe dd is a good eater because she went to nursery full-time from 6 months old and peer-pressure and no-nonsense staff ensured she ate well. However, she is like me and prefers food with a sauce or gravy.
The ds's on the other hand have never eaten stuff like casseroles, spag bol, etc (although they did as babies). One is good at eating vegetables but not things like pasta & rice, the other is a better eater and getting more adventurous all the time but still eats very few fruit & veg.
Maybe if my mother hadn't "pandered" to me and my siblings I wouldn't "pander" to my children, but who knows really?