Ehhh
I mean the resemblance and everything is right there. It would be a little disappointing if it didn't have weight... not that a bloodline is the only way it can have weight. It's actually a little cheap, the way it's cheap for Luffy to have Dragon and Garp so that he was born into it. The way Luffy relates to Roger is better because the inherited will is about who they are and not what they are.
I want Zoro to be of the Shimotsuki clan on the other hand, because he has earned the right to be recognized as their champion in several ways. Ushimaru being his father is the best bet for that unless Kozaburo did a little bangy. It would make sense for Gyukimaru not to recognize him initially... I mean it's not like Buggy knew about Roger and Ace when he met the son. I picture Ushimaru to have a different face.
But we'll definitely find something out when the fight ends