We were in touch ages ago in connection with this question, but I may know more now than I knew then. The main factor is not astrological in the sense of signs and planets, as shown by the fact - or general assumption on the basis of evidence - that lupus is more common among black Africans than among Asians and more common among Asians than among Caucasians. In other words, people are being born on all days at all latitudes so have similar radixes, but lupus is more common among ethnic groups adapted to life in the tropics, less common among groups adapted to life in the sub-tropics and least common among groups adapted to life at higher latitudes. Now, if it were common among black Africans and rare among everyone else, this might be due to a genetic quirk which has spread among black Africans but not among other groups, but the evidence of a gradient from the tropics to the poles suggests that it has to do with adaptation to climate and may be explained by assuming that greenery at the base of the foodchain is most abundant in the tropics and least abundant near the poles. Where it is abundant, there are more creatures, so the creatures are closer together, and infections spread more easily and become more virulent, so the immune system becomes more active as a counter-measure with the drawback that auto-immune ailments become more likely. In effect there is a trade-off between strong immunity and the risk of auto-immune ailments, so the bodies of white Europeans can risk having less immunity for the sake of avoiding lupus, Alzheimer's and so on. It has also been shown that our cells are able to gauge the amount of solar activity, of which a great amount is typical of a green age, and a slight amount of an ice age, so if the amount rises and climates all round the world become more tropical, immune systems become more active, and if the amount falls, they become less active. (I can refer you to the research at need.) The amount has been intermittently falling since 1957, so if relatives of yours are bothered by lupus, this may be good news for them. Is this the kind of information you were looking for?