For teens even somebody between 21 and 25 is "old". Now that I am in the "ancient" category, I see it even more poignantly. If that day I had met Stewart, he would have been too "old" too for me, but I would have certainly made an exception and consider him a pal of my age group!
Miles is a first child, and as such an overachiever, burdened with responsibilities of any kindL he is expected to shine and be a model. ( I am too, so I understand his role).
Stew is the baby, so he always had a protective structure around him and role models galore. He can also be a brat!
Ian had the most difficult karma. The middle child is for the most part the troubled one, and boy he was!
All this comes not from yours truly, but from Wild Thing.