Aren all white cats deaf?
No they are not, although they have a higher risk of being so. The highest risk is for the blue-eyed white cats, since the blue eye colour is caused by a lack of pigment in the eye in the same way as for white hair, and this acts as a measure of how much the pigment has been inhibited by the white gene. The white gene also affects development of the cochlea in the inner ear, so its a matter of how much influence it has had. Think of it as a race during embryonic development between the formation of the hearing sensors and the spread of the disrupting white gene.