Won’t help your good rep if your
Family’s the worst.
Lucrezia Borgia died after childbirth 500 years ago, likely without having poisoned anyone. Not even a single husband! (The marriage to her first husband was annulled, her second husband was probably murdered by her piece of shit brother Cesare, and her third husband outlived her.) Okay, so she definitely cheated on Husband #3, Alfonso I d’Este, but he cheated on her too, and besides which! It was Renaissance Italy; who WASN’T unfaithful to their spouse?
In her lifetime, she was considered to be highly intelligent, being extremely well-spoken and able to say those words in five different languages. Many considered her to be perfectly charming. So how did the bad rep start? Look no further than Husband #1, Giovanni Sforza. He was extremely bitter about how the annulment went down. It might have been murder via Cesare instead, but Lucrezia warned Giovanni so he could flee. He showed his gratitude by claiming that she carried on incestuous relations with both her brother AND father, Pope Alexander IV.
The stories grew from there over the centuries because everyone loves a villain, so why not a whole family of them? Hence the streams of lovers she seduced then murdered, the hollow rings filled with poison, etc. And all, ultimately, because of an awful father and brother and a bitter ex.