What is the relationship your kids and your nephew/niece's kids share?

They'd end up being their cousins, it can get confusing.. and btw I think you should have kids, they may be a handful but there fun..

They are first cousins so their children children and children would automatically be second cousins, third cousins and the list goes on. They do not have to call themselves first, second or third cousins. They are cousins it does not matter how long the family tree is.

In some cultures example in Asia, your son would marry to your brother daughter. This is called incest and it is illegal in the west. It is very disgusting and it has got a lot of medical drawbacks because their kids will inherit incurable illnesses. Even your nephew great grand children are not suppose to have sex with any your kids and create kids too. The blood is the same no matter what or even if there is any difference the resemblance traces will still be there one way or the other.

Family relationships have got limited title or names because the family tree is too long. So everyone will just say that person is my cousin even if the relationship is far apart. On the other hand, you would refer to you mother boyfriend as your uncle or you dad. But he's really not your uncle but such titile is rather for the sake of traditional respect.

They would be cousins.

um they would be cousins.