I have no doubt that Robert A. Heinlein had more to do with the man I grew up to become than any other non-blood relation.
The Heinlein Society
The Heinlein Biography
The Heinlein Archives
And, for "Heinlein's Kids" with money than I, the Virginia Edition of RAH's works includes all his works, including unpublished fiction and non-fiction, letters, and screenplays.
Yes, that's screenplayS, plural...