I would say America, but our comedy and humor comes from all over. The Irish, yes, of course, (and despite what somebody else said) the Jewish people, Black people, etc. all have great humor. I grew up not realizing the British were funny, you know, stiff upper lip and all that.
I imagine there is no where in the world without some kind of humor. OK, maybe the Taliban aren't a barrel of laughs but most nationalities and ethnic groups can be funny.