My mother had all of her teeth pulled out when she was 16. And dentures after that.
My teeth are awful. I had measles encephalitis when I was a few years old and they had me guzzling tetracycline, which was a very new antibiotic at the time.
Not long after that they realized that you can't give tetracycline to children. It stains and deforms the teeth really badly. I'm sure it made a mess of my gut bacteria as well. But I'm still here, so can't complain too much. I remember my grandmother gave me a St Jude pin (patron saint of lost causes), that's how bad measles encephalitis was in those days.
So every dentist I've been to has said that I have the worst teeth in terms of misalignment, ridging and staining, that they have ever seen.
As well as that I have the same really soft teeth as my mother had. As well as being a huge fan of sweet foods and drinks (like my mother's mother). So none of this really contributes to good teeth.
I had 6 front teeth at the top capped about 16 years ago at the request of my ex and it is one of those that has fallen out now.
Most of my teeth are already gone or are broken and need extraction.