My 2 year old daughter never liked eggs. We started buying some from a neighbor who pasture raises his lay hens (and feeds them more chicken-appropriate feed).

She eats her eggs and asks for more. If we run out and I fry up some store bought ones, she refuses to eat them - even when I don't tell her where they're from.

Same goes for chicken meat from the grocery store vs. pasture raised broilers from another neighbor.

When it happened the first time it was something of a canary-in-the-coalmine situation for me.