get_ancestors() 似乎是你需要的功能。如果给定ID和对象类型，它将返回一个祖先ID数组，第一个是最远的父/祖/曾祖/曾祖/等，最后一个是直系父。您可以使用这些信息构建链接。

function parent_id_wpse_142550($object_id,$type) {
  $anc = get_ancestors($object_id,$type); 
  $parent = array_shift($anc);
  if (!empty($parent)) {
    return $parent;
  } else {
    return false;
  }
}

function parent_link_wpse_142550($link) {
  if (!is_wp_error($link)) {
    return \'<h2 class="link"><a href="\'.$link.\'">Return</a></h2>\'; 
  }
}

function parent_term_link_wpse_142550($object_id,$type) {
  $parent = parent_id_wpse_142550($object_id,$type);
  if(!empty($parent) && $parent != 1){ 
    $link = get_term_link($parent,$type);
    return parent_link_wpse_142550($link);
  } 
}

function parent_cpt_link_wpse_142550($object_id,$type) {
  $parent = parent_id_wpse_142550($object_id,$type);
  $link = get_page_link($parent,$type);
  return parent_link_wpse_142550($link);
}

function make_links_wpse_142550($content) {
  $links = \'\';
  global $post;
  $links .= parent_cpt_link_wpse_142550($post->ID,\'book\');

  $terms = get_the_terms($post->ID, \'genre\');

  if (!empty($terms)) {
    $term_id = array_shift($terms)->term_id;

    $links .= parent_term_link_wpse_142550($term_id,\'genre\');
  }

  return $links.$content;
}
add_filter(\'the_content\',\'make_links_wpse_142550\');