I am reading Rita Chabonnier's book Mozart's Sister about Mozart's oldest sister, Maria Anna.  It's really good so far.  I looked her up.  She was a gifted musician as well, but could not pursue her talents.  Though her Father touted her as a musical prodigy when she was young, he saw such talents as unseemly for a girl becoming a woman.

What books have you enjoyed that were about the lesser known family members of famous people?

Galielo's Daughter was really good.

Rasputin's Daughter gave a different perspective.

I just ran across one about Oscar Wilde's niece Dolly that looked pretty interesting, but I'm still pondering whether I want it or not.  She apparently truly put the W in Wilde!

Interesting stuff to look up :)  I think I find the less than famous more interesting reads than the really famous.