To keep to the numbering:

17. You are a bona fide folk singer if:

a) you have nine different guitar capos, including a semi-automatic flipoff
b) your first name is one syllable long, or at most is two syllables that end in a vowel, e.g. Doc, Pete, Woody, Joan, Judy
c) you learned the song on a porch, preferably one with a sofa with the insides sprung out
d) you refuse to make an anatomical pun about “The Londonderry Air”
e) you have “This X fights Y” inscribed somewhere on your instrument, e.g. “this E string fights sexism”.
f) you have a dog named after a colour.

You are not a bona fide folk singer if:

a) you play the Hammond Organ
b) your first name is Brittany (unless you are a boy)
c) your last name is Rockefeller or Windsor
d) you learned the song from your chauffeur or housekeeper, unless her name is Elizabeth Cotten
e) you have a sticker on your guitar that reads: “Baby On Board”
e) you have a cat (whether it comes back or not) or goldfish (see Entry under whales). You can have a horse as long as you race it in England or France.