So what do we know about Franky's father?
1. Was on the Grand Line
2. Abandoned Franky, because he was too much to handle.
Now for Franky to have reached Water 7, but his father to not have lived there. I believe Franky's Father must have been a Pirate. A mean pirate, willing to get rid of his own son. Plus for Franky to be how he was as a kid, you would think he would have some negative, pirate influence to make Cannons and such.
Well, anyone else think it may be possible that… Buggy the Clown is Franky's father?
-Both are humourous.
-Both have Blue Hair
-Both have similar facial structures
-Buggy's best thing is the Buggy Bomb. Maybe even Franky made it as a kid?
-CuTTy Flam : BuGGy
-Buggy has stated he was on the Grand Line before.
So it was just a thought. But wouldn't it be interesting?