her fearful symmetry

I finished Her Fearful Symmetry by Audrey Niffenegger in just over 24 hours.  This would lead one to believe that I really really liked it, which I did...until about 30 pages from the end. Julia and Valentina Poole are 21-year-old American twins who appear to have little interest in college or finding jobs. One morning they receive a letter informing them that  their English aunt, who they have never met has died and left them her estate.  The conditions of the inheritance are that they live in it for a year before they sell it and that their parents not enter it. Julia and Valentina are twins. So were the estranged aunt and their mother. The girls move to the flat, which borders Highgate Cemetery, and come to know the living residents of their building. The story follows the girls as they become involved in the complicated lives of their aunt's neighbors.   I don't want my dislike of the ending to discourage anyone from reading this, because you may not have the same feelings towards it as I do.  I really did enjoy it (obviously...I read it in a day) and am trying not to let one small (although important) plot twist ruin my enjoyment!