There is a huge difference in the effects of thalassemia between major and minor. Most majors have had some impaired growth, although with current treatment programs, this can be minimized. Thals in the past did not have this advantage. I know many thal majors who are below 5 feet in height. Minor may, in some instances affect growth, but not to the same degree as with major. One must also keep in mind that genetics plays a big role and if you are from a background of short people, you can't expect to be tall. Good nutrition can help with growth but don't expect miracles. Most height is gained by the mid teens. After that, there is little that can alter this.