DH was a very plain "British" eater when we first got together. Very much a pie and mash, his Mum was a plain, albeit, good standard cook, from the Midlands.
He didn't like salad or tomatoes, garlic, courgettes, not sure he had even eaten courgettes, couldn't eat shellfish, didn't like fish, or cured meats.....
I'm half Italian, my DM being an excellent cook, and I spent many months in Italy during my life so that's what I ate.
I "cured" DH very quickly. His shellfish allergy we cured by exposure, his dislikes we gave him every day, don't like it, don't get to eat.
Mean, but effective. He now eats everything and particularly loves fish and shellfish, and salads.
It's all to do with upbringing and what you are used to. Our DDs eat everything because they were exposed to it from weaning. They live anything and everything.