Nicolas Grimaldi on Instagram: "“W” sitting is a common sign of imbalance in the lumbar spine. When a child can’t arch their lower back properly, they often default to sitting in a “W” position. This creates a vicious cycle: the imbalance leads to the habit, and the habit reinforces the imbalance. You may even notice darker marks on the skin around the upper lumbar vertebrae from repeated contact and friction with chairs or the floor. This posture is often linked with what appears to be a “short