3 to 5%
Did you mean scheuermann disease? For this diagnosis, genetic factors are more important than environmental ones, but we haven't been able to find specific genes that cause it.
Most likely, it's a combo of genes and environmental influences. In conditions with this sort of multifactoral inheritance, the risk for each child of an affected parent is about 3 to 5 percent, or 1 in 20 to 1 in 30.