Dear WHJ,
Usually people get refusals due to week points in TRV. Visit to brother/sister does not mean anything in the view of VO so VO thinks that you will not leave Canada at the end of trip. This condition (purpose of visit to meet brother/sister) could only be valid if you have strong travel history. Otherwise, you can change your purpose of travel by using some alternate options. I have seen many cases especially in this forum in which most of people get refusals due to week travel history, week purpose of travel and week ties etc.
I can give you my own example. In my TRV, i had applied with strong purpose of travel other than to meet siblings even that my all family (brothers, sister and mother) are Canadian permanent residents. So, i got multiple trv visa with no strong travel history.
In the end, i would advise you, apply your trv case with strong and appropriate points. Before apply, you should focus on refusal points that how you can overcome these points?
Thanks