I had somewhat the opposite problem. I wasn't a picky eater as a child, and I don't have children who are picky eaters, but I was the child of a picky eater!!
Or should I say, the child of a very traditional eater. My mom (dad was not in the picture when I was little) would only cook what she had learned to cook from her own mom, and not even all of that, and hardly ever try something new, even when eating outside of the house!
for warm meals:
plain boiled potatoes every day, except very sometimes mashed potatoes or fries.
to go with that: vegetables, but also always choosing from a very small range.
traditional meat could be pork chops, steak (overdone shoe-sole style), sausages, chicken, beef stew
Very sometimes fish, but then always the same fish: cod.
Never ever ever spaghetti or rice. Nothing exotic such as curry, pizza, etc.
No casseroles, no lasagna, etc etc (let's just say: she had an oven but very seldom used it).
For breakfast: ALWAYS bread with chocolate. My grandmother who lived with us: always bread with strawberry jam.
For the third meal of the day (could be either lunch or dinner, depending on when it was convenient to make the warm meal): bread with cheese (almost always the same cheese) or some deli meat (again choosing from a very small range).
For me, this seemed normal. This is how I grew up, I had never seen otherwise (I was a bit sheltered, too), and I thought everyone ate this way.
But then I started having friends and sometimes visiting them over meal time.
Not to mention, I went to live on my own at 18. In one of the most multicultural cities of my country.
And a culinary world opened up to me.
I have become a very adventurous, versatile cook and eater, and Iove to learn and try new things still, all the time.