spaghetti inheritance

( n.)

   [encountered  among  users  of  object-oriented  languages  that  use
   inheritance,  such  as  Smalltalk] A convoluted class-subclass graph,
   often  resulting  from  carelessly  deriving  subclasses  from  other
   classes  just  for  the  sake  of  reusing  their  code.  Coined in a
   (successful)   attempt   to   discourage   such   practice,   through
   guilt-by-association with {spaghetti code}.

[glossary]