Not the Apostolic Age, but how old were the Apostles when they were called by the Lord?
I don’t think anyone really knows, but here’s my best guess – just my personal opinions: I think Peter and most of the others were close to 30, certainly adults. John was usually referred to as very young by comparison (& apparently lived another 50 or 60 years) so I would guess he was in his teens or very early 20’s at the time Jesus called him. Mark is also supposedly younger, perhaps in his mid-20’s or so. The Scriptures tell us what essentials we need to know, but not details of the Apostles. Since a Jewish man of those times was considered an adult (for religious purposes, i.e., responsible for his own sins) at age 13, they could all have been teenagers, but since most of them were working, supporting families, etc… I would guesstimate them to have been mostly in their late 20’s or early 30’s at the time, with possibly the exception of John, who is traditionally pictured as beardless, and quite young, possibly as young as 18.
Just my thoughts, don’t think the Church has ever given us their ages, and I don’t remember any Saints asking about it!
I do know that it’s traditional that Mary was quite young – girls were generally married to older men at age 13 or 14 as a rule.
We don’t know and there is no Church teaching or tradition on this.
I was wondering how the different ages might effect how Jesus and the Apostles related. For example, what if Peter was older than Jesus; did it influence his choice of Peter as first Pope. Unfortunately we can only guess.