Your first cousin is your son's first cousin once removed.
Your son and your nephew are first cousins to each other. Their daughters are second cousins to each other.
Cousine
The sons of your father's sister are your first cousins.
Nephews are the sons of your brother or sister. Therefore nephews who are not brothers to each other are first cousins to each other.
Your mother's sister's children, sons or daughters, are your first cousins. The children of first cousins are second cousins to each other. That is the relationship between your children, or either sex, and your first cousin's children, of either sex..
Your granddaughter and your sister's grandson are second cousins.
Second cousins.
Your dad's nephew is your first cousin, his children are your first cousins once removed.
You and your first cousin's son are first cousins, once removed.
Your cousins child is your first cousin once removed.
Your uncle's sons and daughters are your first cousins.
Your mother-in-law's brother and his children are not related to you.He is your childrens' uncle and his children are first cousins to your children.