The forum subscription is NOT recursive. For example if you chose to subscribe to the "Tools and Research" forum you will receive an alert to new topics and posts. However there is a "DNA Research" forum located within the "Tools and Research" forum. Even though you subscribed to the higher level "Tools and Research" forum you will not receive alerts from the "DNA Research" forum until you subscribe to that forum. Summing it up, you must subscribe to each and every forum you wish to follow.