Wood release is a kekkai genkai of the Senju clan (Originally the God trees sacred ability / Otsutsuki clan), however, Moegi is able to do it by combining the Water and earth style. How was this possible? We know Orochimaru used to perform experiments on merging Hashirama's cells with small children but the Third Hokage put an end to it.
Moegi did not have the wood style ability while she was younger plus the experiments that Orochimaru did with Hashirama's DNA were destroyed earlier in the series. So how did Moegi suddenly become able to use it at adulthood?