Board Thread:Theories and Speculation/@comment-32457608-20170823143115/@comment-25122992-20170825131531

It's not actually a proof. Just admit it, there is no Haruno clan mentioned in the series, the same way as there hasn't been mentioned any clans like Namikaze, Momochi or Yuhi, despite the characters with forementioned family names being elite jonin-class shinobi or even Kage level. Not to mention a whole bunch of top-class shinobi characters that don't have any surname at all and even almost no info about their direct relatives like Jiraya and Orochimaru.

P.S. Technically, Shizune also has a decent heritage since she's the niece of Dan Kato, a quite skilled Konoha jonin. But, as I already said, the heritage doesn't always determine the level of skills (besides, that's not my own statement, but the statement of Hagoromo).