As you know, lupus is an autoimmune disease, which means that it is characterized by the body developing a reaction to itself. The symptoms in lupus therefore come from antibodies and other reactions against components of the body's own tissues, leading to skin, joint, kidney, and other symptoms.
We do not completely understand what causes lupus. It is most likely that it is not a single factor, but rather multiple factors together, that lead to lupus. For example, there are numerous genes that predispose to developing lupus; these genes are involved in some of the body's defense and immune cascades. However, at the same time, likely environmental factors are also important (such as certain viral infections). One way of thinking about it would be to say that lupus develops in people who have certain genetic predispositions when they encounter the right environmental triggers.
Given that there is a genetic background, the fact that your mother has lupus does put you at at least modestly increased risk of developing the disease. There are currently no medical treatments that can prevent lupus; therefore, taking good care of your general health and regular checkups with your primary care doctor
are the best strategies.