Flat back of the head has nothing to do with IQ. Flat back of the head refers to the abnormal shape of the skull, while IQ is controlled by the development of the cranium during growth and development, and IQ has nothing to do with the skull. Flat back of the head means that the back of the head is not very full, presenting a curvature that is not so obvious, just the appearance of the skull. IQ is determined by the brain, affected by growth and development, if in the process of growth and development, there is a congenital lack of craniocerebral development or acquired craniocerebral trauma injury to the brain parenchyma and other parts of the brain, there may be a low IQ occurs. Flat back of the head can be seen with the naked eye, IQ needs to be tested in a professional organization, there are special evaluation of IQ scale and ways and means, if necessary, you can go to a professional organization for testing.