Prince Idon discovered Atlantis after fleeing his homeland. He arrived during sunset and was so amazed by the beautiful red colours of the sky and the clouds that his hair turned bright red. He became the first redhead and all other redheads descend from him.I came across this story years ago on-line and immediately dismissed it out of hand as it seemed so obviously made up. At the time I was only interested in the history of redheads and had no interest in the modern mythology of red hair - of which this is a classic example.
Coming across it again I thought I'd have another look at it. I thought maybe there might be at least a half-truth in there somewhere. However, I couldn't find any provenance for it whatsoever. Even the name Idon doesn't seem to appear anywhere in ancient mythology. Maybe it stands for I-don't know.
It does appear as an English family name in various different spellings. There's also the Norse god Iðunn (or Idene), a female deity associated with apples and youth.
I guess Idon could also be viewed as a variant on Eden or Odin.
In summary though I'd have to say that this legend is probably %100 made up. It's probably no older than I am. There could be the possibility that it has its origins in some Theosophical work - the legend of the lost continent of Lemuria is very 19th century. However, I'm not hopeful, I'll keep my eye out for anything that may relate though.