What exactly causes Asperger Syndrome?

I often wonder what causes Asperger Syndrome and why it affects me the way it does. I have wondered whether it is caused by some cognitive impairment, whether it is hereditary or whether it may be some digestive problem. Of course there are many theories and one day I am sure we will know. I was surprised to read in a recent report that there is no link to Autism and Digestion problems. I am sorry to say that such evidence is wrong. I am a person on the spectrum and I do get digestion problems. Some foods cause irritation and I have to be careful of what I eat, particularly when I am stressed. You don't need to be a medical expert to realise that anxiety affects the body in ways that disrupt normal day to day functioning. If you are tense a lot your immune system is going to weakened and if you are anxious, your digestion process is going to be affected. When I was younger, I used to have anxious episodes where to eat a piece of toast I had to virtually cut it into strips and I had to severely watch and control what I was eating. I am currently in the process of writing my book on employment related issues but eventually the book will be soon available if I get the chance to publish it. I have written over 11 000 words already and I feel fueled to write it because I am tired of the growing numbers of adults unemployed and somebody has to do something about it. I am focusing mainly on how adults can be employable and how society needs to understand Autism better. I think some of the current findings are incorrect and perhaps or what would be more beneficial is to actually ask persons on the spectrum about how they relate and cope to certain situations. I have heard the vaccine case but I think more importantly we need to focus on underlying causes and whether or not AS is also hereditary.