What is porphyria?

the madness of King George is believed to have been this dreadful disease

Sounds like any one of many symptoms we feel ever day!!!!.

Player #8297262, Porphyria is a sex linked condition, like haemophilia. It's more likely to happen if the Mother and Father are related, which is why the Royal family had so many health misfortunes. Only recently has the British Royal family stopped interbreeding.

Player #13189217, folklore about vampires intolerant of sunlight.