they would be your half sibling
You are each others cousins.
He was the son of Poseidon and a mortal woman.
If your child marry someone who already have children, those children will be your step grandchildren.
2nd cousin
Yes, say if the woman had the child then married your dad, no, but if the boys biological father is your biological father, you are related
He was Apollo's son.
because dads think they are superier over everyone else... they think the next best thing is another guy it doesnt matter if there son or their friend. It's not their fault i dont guess its just that they think that way. My dads the same way..... P.S. theres a word for our dads... Pig Headed
Your sister's son is your nephew. You are his aunt (if you are a woman) or his uncle (if you are a man).
his son is marrying a woman from another ethnic group. he didn't like this.
albert steptoe
They should, but they don't have to.
He would be your second cousin.