You could try to meet her at a book signing or on an Author Tour. Usually though, the best way to contact an author is through the publisher. They will (of course) screen any...
Barbara Kingsolver is 56 years old (birthdate: April 8, 1955).
Barbara Kingsolver was born on April 8, 1955.
Your first cousin's grandchild and your grandchild are third cousins.