Yes, it is hereditary and stress can also add to it. My doctor told me that my number was really high and I told her that so much was going on with me and that my diet was indeed a factor. She gave me six months and if it didn't come down, she was going to put me on something.
I hightailed it and got my diet back on track (not loosing weight but eating properly) and watched for the triggers of stress. Still under a lot of stress but managing it better. You need to take time for yourself and regroup...at least I've learned that.
I had a girlfriend who was doing the fish oil and something else. I'll have to ask her and get back with you. She swore by it. It was another vitamin type. I'll check with her and let you know.