A young man and woman are travelling by train

A young man and an woman are travelling by train, and the woman, after looking closely at the young man, leans forward and says,

“Excuse me, young man, are you Jewish?”

And he looks up from the book he is reading and politely replies

“No ma’am, I am not Jewish.”

A few minutes later the woman leans forward again and says,

“Excuse me, young man, are you sure you’re not Jewish?”.

And he looks up once again and politely but firmly replies,

“No ma’am, I am not Jewish!”

There is silence for a long while, and then the woman leans forward yet again and says,

“Excuse me, young man, are you quite sure you’re not Jewish?”.

And the young man eye-rolls inwardly, grits his teeth and says,

“All right, yes, I am Jewish!”

And then there is silence for many minutes.

And then,

“That’s funny,” says the woman,

“you don’t look Jewish.”