I was never allowed to leave food on my plate either, precisely with the argument that my grandparents had suffered hunger in the war. Which they had, and most of my generation has too been raised this way. I even know the etiquette around table placements.
Same here. Both my parents grew up poor. My mother had 10 siblings and my father was an only child. We were required to have dinner together on Sundays. Any other day, my father wouldn't eat with us. He was in the military before he met my mother so he also insisted that we go to ethnic restaurants and try new foods.
Our family sat together for dinner every evening when my husband came home. I never forced my kids to eat but that lead to a problem.
MJ: <Daughter> please eat your dinner.
D: No.
MJ: OK, but you'll be hungry later.
D: No I won't.
MJ: <looks at hubby for backup. Met with silence>
Fast forward to midnight
D: Mommy, I'm hungry.
MJ: Honey, I told you to eat your dinner earlier.
D: I want something to eat.
MJ: I'm sorry honey. You should have eaten your dinner earlier (I wasn't going to let her starve, btw).
Husband: Get out of this bed and go feed your daughter.
MJ: <gets up and gets daughter food>
Repeat this scenario for about a month
Husband: Go feed her.
MJ: I'm exhausted. You do it.
Husband: <gets ticked but gets up to feed her>
Next day at dinner
MJ: <Daughter> please eat your dinner.
D: No.
Husband: Eat your food NOW!