The term 'cousin' is a bit imprecise, here in Bhutan. Well, so are the terms 'brother' and 'sister'. Those two terms can refer to someone from the same village. When you get 'cousin-sister' you know things have become a little twisted. When my students bring their 'sister' to collect their school reports, I have to ask "Real sister?"
Wikipedia is very helpful, with a mathematical definition for us (click on it for a more readable size):
Got that? Maths .... the universal language, eh?
What the heck is 'consanguinity'? Is that some kind of integral?
I am working on a modification which includes the Bhutanese term. I think I will need x and y to be negatives ... or imaginary numbers.