I should and maybe will write a book on the subject of siblings of the talented. Though I know there is no such thing as a category of human being, I have begun to think that this is a special category, entitled to some respect and attention.
One of the most precise listeners I have ever taught is one of the least naturally musically talented. His younger sister, both severely developmentally challenged and blind, has a musical capacity that is astonishing even given its limitations. This older brother listens for every small sign of content coming from the disabled sister and extends that quality of attentive, almost devotional listening to every note he plays himself.
The desire to play, to have what comes naturally to the other one, no matter what kind or extent of effort is required is truly noteworthy.
I have seen it before. Years ago I had dinner with a couple of psychologists who were celebrating passing their certification exams. One, new to me, made more noise than anyone I had ever seen. I telephoned her the next day to ask if she had ever studied music. Silence. Her older brother had been the talented one in the family and there was not enough money for her to have lessons; she had always craved music in her life. "What do I do?" she asked. Cut your nails, get a piano, and give me a call. She did.