Ok i know i am a bad title maker so let me explain the title.
Is Dragon the only son of Garp?
Is Luffy the only son of Dragon?
I never thought about it until now that If Luffy can have a blood related brother or sister. Same question can be asked about Dragon, if he has any brother or sister. I had a really crazy theory that Shakky is daughter of Garp and since she became pirate, Garp chased her to capture her and bring her on the right track. Asusul Garp failed and let her be what she wanted to be. well thats my theory and you all know that my theories are crazy so feel free to comment on them and agree or disagree.
I have a Indian background so i watch bollywood movies a lot. They all have same lame story line. A happy family. Good mother. bad father. two children. Father runs away with one child and mother raises the other. in future at one point both brother meet and beat the villan take the heroin. happy family back together. happy ending. But does that can happne in One Piece. I know that Oda is 1000000 times smarter then those lame bollywood movies story writers but still can it happne in OP.
So to get back on the point