(defstruct person
    name     ; a string
    address ; the person's street address
    gender ; the symbol 'male or 'female if known, nil of otherwise
)

Otherwise, where does the paren go?  Before the comment?
Inconsistent.  Also, if you want to add a field, you just hop
to the end of the last field line, hit crtl-J and type away ( emacs ).
Often while editing and dubugging a function I'll leave naked
parens, then tighten them back in when I know it's perfect.