ow young is too young to play the Doctor from Doctor Who?

In Doctor Who, we've had actors who are a wide variety of different ages who have played the Doctor! Peter Capaldi is 57, & Matt Smith was 25 when he was first offered the role. However, I don't think there have been any Doctors under 25 so far. But what age do you think a person should be at the youngest to play the Doctor? Is 21 too young? Is 18 too young? If you ask me, maybe an actor should be 21 or over to play the Doctor, since 18-year old's are really properly grown up yet, & will by the time they'ere 21. But what do you reckon? Also, I know that there is no sert answer to this question. But I'd like to know everyone's opinions. Please post your opinion.

I could see a 5 year old pull it off.

This question implies age matters with a character that could literally be any age or gender. The ability to handle the nuance of the role and media scrutiny are the only important factors. It might make younger actors less likely to be good for the role, but there's nothing that categorically denies them the potential to be good.

I would love to see a scene for Two Time lords. One portrayed by a Old Actor and a Young Actor and having the Young Actor telling the Older Actor to stop being a silly youngster and act his age.

But yes. An 18 year old could portray the doctor....even though the new show is pure tweeny bopper crap.

Technically he could return looking any age, but personally I don't want to see some teenager playing The Doctor, let alone a child. When it comes strictly to casting I'd go with someone who is at least 20.