The ‘Moron’ jokes were the big jokes when I was a kid.
Like “Why did the Moron throw butter up in the air?”
“To see a butterfly”.
I never heard a racial joke until I went in the Army. My parents wouldn’t have tolerated things like that.
The closest I ever came to saying something like that was when I said “Jap” and my Dad told me not to use that term but to say Japanese. My Dad had been on General MacArthur’s staff and after the Japanese surrender, and as the Occupation got under way, orders were issued not to use Jap and show respect to the Japanese people.
Your Dad clearly was not a Marine. EVERY WWII Marine vet I knew, who fought in the Pacific, said “Jap,” and they probably continued to say it up until they died in old age.
Perhaps you are unaware of the profound hatred the Marines and Japanese had for each other. It was visceral.