I see food pickiness as a play for control similar to tantrums, nothing more
My father felt the same way you do. As a result, it wasn't until my 20's that I discovered the reason I felt like crap ALL THE TIME was because I was lactose intolerant. I cut (lactose-containing) dairy from my diet and like magic I feel so much better.
Also, the whole 'clean your plate thing'... I personally feel it's a terrible terrible thing to teach a child. We (well, nearly everyone) are born with the built-in ability to discern if we are hungry or not. Forcing children to eat things they don't like, or when they are not truly hungry, over and over again, for years, destroys that built-in mechanism.
I, personally, try to cook meals everyone in my house enjoys, and thankfully my children aren't super picky regarding healthy foods (both kids like broccoli, carrots, peas, califlower, spinach, etc) but no one is required to eat, ever. If I cooked something new, they are not allowed to simply declare it 'yucky' or 'gross' - we make them at least taste it. If they don't like it, no worries.
