How can I set the first link in my nav menu to simply be a drop-down to some other pages

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Use the wordpress Menus under Appereance -> Menu and wp_nav_menu instead of wp_list_pages in your theme. If your theme is recent, changes are that you are using it now.

Under Appereance -> Menu

  • Create a menu, label il “Site menu”
  • Create a custom link About, and assign it # as destination link
  • Drag and drop your about pages after About

See this page of the codex on the menus