I felt like since Gene is my fursona they were kinda the least integrated character in my toon story so I set out to fix that by establishing them as a former 3D platforming mascot back when they were a kid. This was just done real quick to as a showcase of what the characters look like today.

I PROMISE GENE DIDN'T KILL THAT COW OK!!!
The short summary is Madeleine (ie: Dr. Mad Cow's actual name) was already in her mid 60s when Gene (then called Flydo) defeated her and that was over 20 years ago canonically. She died of natural causes due to being FUCKING OLD.