The thing that bugged me about the prequels is that they didn't make Obi Wan old enough... because he looked at least over 70 in Ep4, but if Obi Wan looked to be about 25 in Ep1, he would would still only look about 55 based on the estimates by Goktimus above.

Unfortunately, I think they needed to show Obi Wan as a padawan first in Ep1, but it wouldn't make much sense that he'd still be one at about 40 if they start their training by the age of 5. (unless he was a reeeeally slow learner )