Having a natural preference to complete more tasks with your left hand rather than your right. Being able to successfully and skillfully do things with the left hand. Left handed people are often brilliant, more so than right handed people. If not brilliant, which is very possible, they are usually creative in some aspect.
Left handedness is NOT always passed on through genetics; Every person in my entire family for generations have all been right handed, but all of a sudden, here comes me and my two sisters. We are all three left handed.
Allison is left handed because she writes with her left hand and does other things with her left hand as well.