Not blood related, but Ghetsis technically is N's father. In the opening cut scene for Black and White before you get to the Title Screen, it shows an image of N as a child in the woods with a Darmanitan, Zorua, and a few other Pokémon by his side. It's implied that N's parents left him in the woods, then Ghetsis found him and wanted to use his power of hearing Pokémon's inner voice to take over Unova.
