Most wimmin are like that mate. Ask if they want you to replace a blown light bulb whilst you are there and they'll sigh and say "No, that's OK, don't bother, I'm happy to sit in the dark". Then, years later, use it as evidence when they tell you what a heartless, selfish b@st@rd you have always been. Just because she is your sister doesn't change the basic fact that she will behave like a wummun. Send her flowers and she'll tell you, in five years, how thoughtless you were for putting the pollen in her house when she was having breathing difficulties.
PS Note well that she has enough breath to phone you and talk ......
