Is that really William, Thomas, Patrick/Patricia, James, and David? :)
It drove my father nuts that his kids ended up not calling themselves the "original" name, but a shortened version of it. We have a Joseph (Joe), a John (Jack), a Margaret (Peggy), etc., etc., etc....
Yes, they all have the full names on the birth certificate. We usually call James "James," but my mother insists on calling him Jim.
I don't blame your dad. I'm tired of all the alliterate, lazy (that's what it is) abbreviations of already-common names - esp. 2-syllable names (Robert)! Can't any1 bear to speak 2 syllables?
Our local show host makes cracks about all the "Bobs" he gets who call in. Sometimes he just gets flip and guesses the man's name (or rather, specifically nickname) is "Bob". "It's the 'Bob' show, ladies & gentlemen!"