In surveys, 80% of the parents of deaf children have normal hearing. According to epidemiological surveys, the prevalence of common deafness genetic mutations in the Chinese population is as high as 3%-5%. If normal hearing parents carry the same genetic deafness gene, they are at risk of having a deaf child. When parents carry the same disease-causing gene like GJB2 and SLC26A4, there is a 25% chance that the baby will be born deaf. If the couple has a second baby there is also a 1/4 risk of deafness. In addition, like a pregnant woman who carries the drug deafness gene, her hearing can be normal, but her children both carry the drug deafness gene and are at risk of lifelong deafness from the use of aminoglycosides like kanamycin, gentamicin and streptomycin during subsequent growth and development due to fever and other illnesses.