There is anecdotal evidence that Lupus and/or other auto-immune illnesses might have a genetic link, but nothing has been scientifically proven. That is, there are people that think it's genetic, but....that's it.
There is not really anything indicating you have the same disease simply because you have the same ANA test. An ANA test is not able, by itself, to diagnose Lupus or any other illness -- it takes a particular set of symptoms to complete diagnosis.
Lynnwood, Lupus & Sjogren's ModeratorDIAGNOSING LUPUS & LUPUS RESOURCES
"Life is far too important to be taken seriously" - Oscar Wilde