Why was Cowen easily seen to have been Cohen?

Question

In Agatha Christie's book The Listerdale Mystery, in the story Swan Song, there is the following qoute:

It required no imagination to realise that his father's name had been Cohen.

This comes after a description of Mr Cowen, the agent of an Opera Singer.

The description is:

He was a tall man, clean-shaven, with a frame rather too well covered, and clothes that were rather too faultless. His hair was very black and shining, and his teeth were aggressively white. When he spoke he had a way of slurring his 's's' which was not quite a lisp, but came perilously near to it.

Why is it then relatively obvious (i.e. it requires no imagination) that Mr Cowen's actual surname is Cohen?

Answer 1

I dug up the quote on Google Books, as I believe it is relevant to the question exactly how the sentences are joined together. The full paragraph reads:

He displayed neither resentment or surprise. Mr Cowan was indeed accustomed to the vagaries of the artistic temperament. He was a tall man, clean-shaven, with a frame rather too well covered, and clothes that were rather too faultless. His hair was very black and shining, and his teeth were aggressively white. When he spoke he had a way of slurring his 's's' which was not quite a lisp, but came perilously near to it. It required no imagination to realise that his father's name had been Cohen. At that minute a door on the other side of the room opened, and a trim, French girl hurried through.

I do not read the sentence in question as a comment on the previous description, but rather as a continuation of it: apart from the other characteristics just described, Mr Cowan looked like he should have been named Mr Cowen. The most common stereotype about Jewish looks is probably that of the large, aquiline nose. My guess is that is what is intended by the sentence.

Answer 2

The only stereotype I know of relating to the name Cohen is that it's a very common Jewish surname, coming directly from the Hebrew כֹּהֵן‎ (kōhēn) meaning "priest". From Wikipedia:

Bearing the surname often (although not always) indicates that one's patrilineal ancestors were priests in the Temple of Jerusalem. A single such priest was known as a Kohen, and the hereditary caste descending from these priests is collectively known as the Kohanim.

Thus, if someone is described as being clearly descended from a Cohen, the only thing I can think of is that their appearance must be somehow very Jewish. I'm not familiar enough with these stereotypes to be sure, but perhaps the accent described is influenced by Yiddish? Anyway, this must be what the passage is supposed to mean, as that's the significance of the name Cohen.

(Interestingly, Cowen is an Irish surname, with no Jewish connections as far as I'm aware. Presumably the surname change from Cohen to Cowen, if indeed there was one, was part of a reasonably common practice among Jewish families in those days to change their surnames to less Jewish-sounding ones.)