You ask, "Is lupus a genetic disease?" The answer for most people is "no". Lupus does not have a strong 'genetic tendency' seen in many other diseases, but there is evidence emerging that a small but definite genetic tendency exists.
As lupus becomes more recognised and more readily diagnosed there are clearly more families, in whom a lupus link exists, and it is these families which are providing important data for research.
The advice of lupus specialists, therefore, is that if there are no specific symptoms, it is probably not necessary to test. If, however, you are anxious or as in your case there is a family history of lupus, and there are symptoms that may be related, then it is far better to know what is going on. The screening test is the ANA. If this is positive, the DNA Binding test may confirm a diagnosis.
Professor D'Cruz talks about whether you should have your children tested for lupus here.