Pyschopath Test?

The Shining 1980

This is a puzzle that was supposedly designed to see if you're a psychopath.  It has gone through a few changes each time I read it but the core is the same...Here it is:


A young woman is at her mother's funeral. She meets a man she had never seen before, but who's there as a part of family. She instantly falls in love with him but doesn't get any contact information for him. A few days after, she kills her sister. Why?


I solved this test very quickly..Are you scared yet?