I'm currently struggling with displaying custom taxonomy terms in a WordPress theme, and I can't seem to get the desired output. I'm using a custom taxonomy called genre, which is attached to a custom post type. The problem is how I need to display the taxonomy terms on a single post page. Desired Output: I need to display parent categories with their subcategories in the following format: Fiction (Cyberpunk, Timepunk (Steampunk/Paropunk)) | Fantasy (Heroic Fantasy) The Problem: At the moment, I'm using the following code in my functions.php file to generate the output: function get_taxonomy_output($terms) { if (!is_wp_error($terms) && !empty($terms)) { $parent_cats = array(); $child_cats = array(); // Sort categories into parent and child categories foreach ($terms as $term) { if ($term->parent == 0) { // This is the parent category $parent_cats[$term->term_id] = $term; } else { // This is a child category $child_cats[$term->parent][] = $term; } } // Form the output line $output = array(); foreach ($parent_cats as $parent_id => $parent_cat) { $output[] = build_category_output($parent_cat, $child_cats); } return implode(', ', $output); } return ''; } function build_category_output($parent_cat, $child_cats) { $parent_link = '<a href="' . esc_url(get_term_link($parent_cat)) . '">' . esc_html($parent_cat->name) . '</a>'; $output = $parent_link; if (!empty($child_cats[$parent_cat->term_id])) { $children = array(); foreach ($child_cats[$parent_cat->term_id] as $child_cat) { // Check if the current subcategory has its own subcategories if (!empty($child_cats[$child_cat->term_id])) { $children[] = build_category_output($child_cat, $child_cats); // Recursively build child categories } else { $children[] = '<a href="' . esc_url(get_term_link($child_cat)) . '">' . esc_html($child_cat->name) . '</a>'; } } $output .= ' (' . implode(', ', $children) . ')'; } return $output; } And in single.php I have this code $categories = get_the_terms(get_the_ID(), 'genre'); $output_genre = get_taxonomy_output($categories); In the place where I want to display subcategories, this is displayed: Fiction and Fantasy (Fiction (Cyberpunk, Timepunk (Steampunk/Paropunk), Fantasy (Heroic Fantasy)). It should be like this: Fiction (Cyberpunk, Timepunk (Steampunk/Paropunk) | Fantasy (Heroic Fantasy) I attach an image of how it looks in the admin panel. I am trying to make code that will be as optimized as possible and meet all Wordpress development standards.