My wife just confessed to me that she started giving oral to her twin stepbrothers starting at 14 and they were 16. It was only a few months after her mother married their father and moved in with them. She said they offered to drive her places and other things in exchange for her doing that.
She said she did it to each of them a few times a week until they turned 18. We have been married for 3 years and I considered them almost like brothers. Now I have no idea how to treat them. They are both now married with children.