10 Spider-Man Fates Worse Than Death
2. Killing Your Wife With Your Radioactive Semen
When Peter Parker was bitten by a radioactive spider, he gained amazing superpowers, which was great! Unfortunately, the word "radioactive" was always in the back of Pete's mind, and for a good reason — he was concerned that his radioactive blood might somehow endanger the people closest to him.
Over the years, this concern manifested in hesitation to have children and other areas a person might be wary to venture when their blood was literally radioactive. For the most part, his blood never caused any real problems for the people around him, but he should have been worried about his other... fluids.
On Earth-70237, Peter Parker was married to Mary Jane, but she wasn't as lively as she is over on Earth-616. In that reality, she's dead, and after Dr. Octopus died, his somewhat sentient tentacles dug up Mary Jane's body, which caused Pete to recall how she died of cancer.
She developed cancer due to the prolonged exposure to Pete's seminal fluids, which makes a lot of sense when you think about it for more than a second. After she died, Pete decided to hang up his spandex for good, having missed her passing by a brief moment, leaving him to live on, knowing he killed his wife.