title: wordpress test if custom taxonomy term is child of another term
body: <p>how can i test if a wordpress taxonomy/term page is a child of another term? For instance, if i have a taxonomy for "portfolio-categories" which is hierarchical.  my top level terms are "digital" and "print".  under print, i have "television".. and a few others.  if i am on the "television" archive, is_tax() is true as is is_tax('television') but not is_tax('print').  basically i'd like 'television' and its siblings to behave one way while the children of "digital" behave another.  </p>
  
  <p>is this possible or would this be best served by separate taxonomies?</p>