Because Sanji looks so much like his father too right? Luffy and Dragon? Helmeppo and Morgan? Zoro does NOT have to look like his father. I don't look like my father, guess I'm not related to him after all! Given how much of a cunt he is though, I don't mind though, LMFAO!
You guys are are amazingly narrow minded but feel free to enlighten us with your clearly far superior theories whilst you're at it please. A lot easier to criticise then actually make risky claims, theories and such.
Zoro might resemble his mother more. Or he just happens to look more like Ushimaru than his father/Green Bull. In a series with so much fantastical elements, you guys love to nit pick the most asinine, petty shit.
If you turn out to be right about him not being related than congratulation, stroke that ego of yours as I know you will but if you look at all the stuff I posted and still think there is absolutely no possibility of it, then I pity you, I really do.