Nightcrawler's powers, physiological differences aside, also manifested when he was tossed off that bridge. Scott's manifested when he and his brother were pushed from the plane. etc.
"We come into this world alone and we leave the same way. The time we spent in between - time spent alive, sharing, learning together... is all that makes life worth living." - Jean Grey
I was being loose with the term. The point I wanted to stress is that Jean didnt first develop her TP as an adult
Multiple Man had his at birth. The M twins had theirs by 8. There's also Manon and Maxine. Ditto on Artie, Leech and Franklin Richards. Many mutants get theirs before teen years
If they ever do the rumored Moira X series I wonder if they will have any call backs to the times she interacted with Jean/Phoenix. It could be interesting (or horrible depending on the writer - and this is if the series ever comes to fruition).
The original Phoenix years were great for Jean and I think of them fondly as well. I loved that Teen Jean got to interact with Phoenix/Jean in the Generations issue.
I would love to see this followed up on if they ever go back and fill in gaps about Moira's past with the X-men. Jean and Xavier are so close but I feel often times they mainly focus on Scott and Xavier (they are very close as well but Jean was his protege). It was so fitting in X-force that Jean spoilers:end of spoilers. *Spoiler tags for those that may not have read the current X-force run.
got to use cerebro to bring Xavier back.
I love that John Byrne paid so much attention to details :
When Jean first transformed into Phoenix (Claremont/Cockrum) her suit had a very tiny Phoenix logo in the black triangle. When she fought Magneto (Claremont/Byrne) the phoenix logo was till tiny. When Byrne draws those flashbacks here, he keeps the phoenix logo tiny, as it should. When Moira is testing Jean's powers, we can't help to notice that the Phoenix is getting bigger. That's amazing. It's not only foreshadowing the plot, but also highly symbolic. Most of artists wouldn't pay attention, and would draw the flashbacks with the big Phoenix logo. Missing the point of its symbolic.
About it, I noticed that most artists who draw this iconic moment (Phoenix rising rom the water) they always draw a big/huge phoenix logo. Sometimes then even forget the black triangle. As I said, they don't care, or they don't know the character history/legacy.