The AAO officially called it in 2019: pressing your tongue to the roof of your mouth does nothing to reshape adult bone, because the palate finishes fusing in your early twenties and stops responding to tongue pressure entirely. The jawlines you see in mewing before-and-afters are almost always just weight loss, better posture, or a different camera angle. Hundreds of millions of views later, the biology has not changed, only the audience believing otherwise has grown.