Your grandfather's son's son could be:
Your sister's son is your nephew His sons are your grandnephews, and his daughters are your grandnieces.
Your son's children are your grandchildren.
Your sister's son is your nephew His sons are your grandnephews, and his daughters are your grandnieces.
They share a common Grandparent. That makes them first cousins.
your cousin
Your niece's son's son is her grandson. He is your great great nephew and you are his great great aunt or great great uncle, depending on your gender.
Sons would be plural and son's is possessive. Tickyul
basiclly there called brothers .-.-.-.-.-.-. basically* for one... and two no, they wouldn't be called brothers. If it was their parents sons then yeah, but if it's the sons of brothers then they'd be cousins. That's practically like saying one brother got married and had a son, then the other did too and had a son as well. The relation of the sons would be cousins.
You do you call your sons's son your "grandson" !
When I first saw his picture I though "that has't to be Tim Roth's son but I did a google search and there does not seem to be a relation. Tim Roth actually only has three sons who are named Jack, Timothy, and Cormac. (Tim Roth's name was originally Tim Smith so there is very little chance of relation)
Well, You want to be able to have a trusting relationship. Where the son feels like he can go to his dad for anything he needs. And you want the father to be able to trust the son as well.
The sons of your son-in-law's siblings are his nephews. You are not related to them.However, your son-in-law is married to your daughter. The sons of her siblings are also your son-in-law's nephews. They are your grandsons.