My sister keeps asking me to babysit her child, especially since she has had another recently. She does not really contact me other than to ask me to do this, and this has been the case since the birth of her first child. I am currently doing a phd so really busy around a demanding job in education. I therefore only do it when i can but even then i am having to use free time that i need to study in. I did ask her why she cannot get a childminder (both her and her partner earn good money and live in a big house whereas i rent a shared house and work a job in which i have a lot to take home) but she says that her boy won't respond well to a stranger. It is true that he is a bit needy but i feel that is her deal. I feel very selfish for not being available as and when she needs me, especially as it is probably only every two weeks that she asks, but it annoys me that she sends sweet emails with pictures only when she wants me to do this and seems to have little understanding of the pressures in my life- financial, security of my home, and a heavy workload. It is probably worth mentioning that i am childless at 40 and trying to work towards having my own family though this is fraught with issues- living in shared accommodation in London being just one, so this might contribute to a sense of injustice that i am just helping build her life. The first time i did it she offered money which i declined as i love my niece but since then she has not and this adds to my sense of just giving to her when i am not sure she has given much to me. Is this totally out of order? Please help!