Re: The Official X-Related Questions and Answers Thread
The cosmic ray spaceflight of the Fantastic Four, Peter Parker's spider bite, and the enrollment of the X-Men at Xavier's school all happened roughly 10-15 years ago. There's no exact number, since time moves differently (and inconsistently) in the Marvel Universe.
Cyclops, Archangel, and Beast are all in their late 20's to early 30's (Beast is definitely at least 30, as he was the oldest original X-man and had his 30th birthday some time ago), and Iceman is in his mid to late 20's. Storm, Colossus, and Nightcrawler are around that same age (though I think they're closer to Iceman's age than Beast's). I think Rogue is about Iceman's age or slightly younger. The original New Mutants are in their early to mid 20's. Generation X is still in their late teens. Psylocke is the exact same age as Captain Britain, however old that is, and god only knows how old Kwannon's body is physically.
The timeline moves the same throughout the rest of the Marvel Universe (more or less). Cyclops, Spider-Man, and the Human Torch are all about the same age.
Some characters age differently either due to their origin stories or writers refusing to change the characters. Magneto, Professor X, and Juggernaut are all in their 70's-80's because no one has updated their origins that involve the Holocaust and Korean War. Franklin Richards (son of the Invisible Woman and Mr. Fantastic) has bounced forward and backward between the ages of 7 and 12 for years. I swear he was 12 at some point during the 90's, but he was 9 in the recent Fantastic 4 Christmas issue.