To be fair, unless we're speaking about Storm(?) and the O5, characters don't get their origins told / explored by the original creator.
Not even sure Scott's, Hank's, Warren's and Bobby's origins (the stories published in X-Men Vol 1) were written by their creators in the first place.
Example. Lee/Kirby idea of Warren was "rich white boy with wings". It was Roy Thomas who decided that Warren had been a superhero on his own. I know it's a small detail, but it's something that would heavily change the whole character of Warren, especially retroactively change how you should perceive him during a re-read of the first X-Men Run, since he was already committed to a "protect the people" mission before becoming Xavier's student.
I haven't checked, but I think the other origins stories were also written by Roy Thomas.
*Also, points to Wolverine*