It is admirable that you went for drawing despite everything and pursue it. You must love art seriously!
And a hobby I think is what I like and what makes me happy doing. Doesn't much matter if I'm not good. So it is sad that your sister stopped drawing just like that, hope she finds the fun in it again.
ps. my releationship with my bother is more like a fight between cats and dogs so not sure I can call that healthy :D.