My teeth & many other childrens’ were permanently stained yellow in the 60’s due to an antibiotic prescribed. We didn’t even have our permanent teeth, still baby teeth. My younger brothers were worst than mine. My older two siblings teeth are fine. My Mom couldn’t remember if just us younger two took the medicine and not the older two so can’t determine if age a factor. Spent lots money in the 80’s for “whitening” which never really worked. That antibiotic is no longer prescribed for young children.

So yeah, it happens…