Very interesting topic!
My DS eats almost everything but one of his real dislikes were peppers and eggplants. I keep him exposed to them as we eat them (even if not often, because as I know he doesn't like I tend not to buy often). Eggplants, he actually started to eat a little, even if he is not a fan of them, when he was 3 or so. But peppers, I thought it was a real dislike, as he could not eat anything where they were included, even if hidden. Since one months a go, when he tried them again and he actually ate few pieces, saying he likes. So, definitely, keep offering, as tastes change a lot over time.