Definately carry on with your research. My Dad didn't want me to research our family tree, I knew he didn't have a happy childhood and I think he didn't want me to find out a few porkies he had told. However by researching I found the address he was born in, in Wales, and about a month before he died after a long illness and he longed to visit his youthful home he wasn't able to travel nor was he able to remember the address.
I had it and was able to bring it up on google maps and show him. To see his face, you'd have thought I'd transported him there.
The lies I have found out make not a jot of difference to my memories of him and my feelings, but helped me cope with a difficult time and helped me really understand the circle of life and how we can keep these people alive. If we don't tell their stories then they truly die. Research keeps them alive.
Your sister may one day be happy about your research, or maybe her children will want a sense of where they came from when the get older.
Enjoy your hobby for you and others that will come after you.
Tracey