Usually it is not harmful. But in rare cases it may cause the following Children do not use their core muscles much which may lead to weaker shoulder and wrist & may eventually affect fine motor development. Children with w position have decreased trunk rotation between right and left and may lead to decrease bilateral coordination It may lead to some postural problem and results in back pain in long run Constant W sitting may lead to In toeing gait/ Pigeon gait due to inner side muscle weakness in long run