ДНК S04E08 - Выпуск 412. Мама слепого музыканта?

The mother so started the illness of her three-year-old son that the boy went blind. He was removed from his family and transferred to a specialized boarding school. The boy grew up, and 14 years later his biological mother showed up. But why doesn't the guy remember his mom's appearance or voice? And why does the alleged mother need to return the future graduate of the boarding school to the family?