Years ago I read these two books when I was definitely way too young. They belonged to my DM and I was pre-teen when I read them hence the hazy recollection. I was forever raiding her book collection and if I thought my DD reads some of the stuff I read before I was 15 I think I'd lock the bookcase!
I think Roots was read many times before I was a teen and North & South was a firm favourite along with Rich Man Poor Man and Kane & Abel!
The first is a book by someone like Barbara Taylor Bradford, maybe Jackie Collins. It's about a girl named Jazz and she goes to see her Dad and ends up sleeping with his friend and her dad goes mad. I remember it was set in the USA and her dad came to see her and "she smelled like sex" that's literally all I have other than I think she had curly long red or blonde hair. Not a lot to go on! Definitely has an 80's vibe.
The second is set in the UK. It's possibly set pre WW1 and it's about a working class man with a young family who can't work because he's cut his hand on his fish knife. He ends up selling trays of cooked fish and becomes a millionaire and his kids become entitled. I don't think it had a particularly jolly ending to be fair and I think that when the man died he leaves his fish knife to the eldest son to remind him where he came from. I want to say it's called Acrefair or something like that.
Totally random but both these books bug me from time to time so I'm calling on the powers of Mumsnet to find them!