It depends on the individual. Everyone is different.
Since you mentioned alcohol, the same applies... different people have different tolerance levels for alcohol. I've seen small women drink more before getting drunk. I've seen big guys get drunk on less alcohol.
As for deafness, we're all deaf for some reason. Some deaf people also are affected by Usher Syndrome. Some aren't. I'm deaf, but I'm not affected because my deafness was caused by something else.
