Answer:
hmmmmm genetic inheritance has nothing to do in this aspect, cause if there's something role of gene then all 5 of them would have have suffered some disability!
here's my opinion : A stunning number of teens have lost a little bit of their hearing - nearly one in five - and the problem has increased substantially in recent years, a new national study has found.
Some experts are urging teenagers to turn down the volume on their digital music players, suggesting loud music through earbuds may be to blame - although hard evidence is lacking. They warn that slight hearing loss can cause problems in school and set the stage for hearing aids in later life.