It is sort of possible. The method i would use is to create a page, lets say its called ‘Genre’ which will appear in your navigation once published. You would then create another page, give it a title, lets say ‘Hip-Hop’ add the content and assign a Page Parent [Half way down] status by selecting ‘Genre’ from the drop down. Your sub page will now appear in your blog. You can then use css to hide all sub nav links on page load and then set hover styles so they display on hover of the original parent page ‘Genre’. I’m sure that would do it.
Hope that makes sense