Gamma GT high levels

I have problems with my gamma GT levels, because I can't decreased this enzyme result. Usually my results of the Gamma GT are between 110 and 180 U/L, when I tested it, however the other enymes TSGO, TSGP and Alcaline phosfatase are normal.  I stopped drinking alcohol, about five years ago, but what I used to drank before that wasn't not to much. I really want to know what is going on with my liver. I don't know if this is a genetic situation, because my mother and my sister had this same problem, always had high levels of gamma GT during many years, now is normal I guess, but I'm still very worrying, hope that someone else help me on this,
Thank you