B.C.
Art is so much more than drawing/painting!
There's sculpting, pottery and kinetic art (mobiles, etc),.
There's stained glass work (lamps, sun catchers, etc).
There's basket weaving.
Music and poetry are also artistic - and even if she doesn't play an instrument - she might want to sing.
I think, rather than doing something because her brother does it - she should explore till she finds an interest that she can make all her own.