Board Thread:Theories and Speculation/@comment-27821571-20160915183730/@comment-734582-20160916101351

I want to point out that jinchuriki can "steal" their Biju's power passively (Naruto's seal) or actively (e.g. how Naruto confronted Kurama).

In Gaara's case, remember that as a kid, the sand was likely his Mother's (a relatively small amount he keeps in his gourd) whereas as an older Jinchuriki, he was almost Shukaku's plaything and repeatedly partially transformed.

So, all that really needed to happen is for Shukaku's power to rub off on Gaara. However if Shukaku never used Magnet Release via Gaara, he wouldn't have it.