Copyright is implied with the written word, but he doesn't own the copyright to the documents themselves.
It's just nice if you ask him if he minds you making copies for the kids, he did go to a LOT of work to research the information, and no little expense if he did it as I do, with Ancestry.com, and trips to Salt Lake City to go to the LDS Family History Library...I can't imagine that if he gave them to you with no charge that he'd want to charge you for copies for the kids...