Barking's idea of us giving a "top to bottom" account of our lists is a good one, also links with onset of LS /LP with hormonal changes could be really helpful in either discounting its effect or otherwise.
comments about other family members being LS sufferers or having other auto-immune diseases would help too.
Personally I have no doubt at all that it is an auto-immune disease though its trigger(s) evade me.
Okay then, my list.
Had LP all over except vulval area from scalp to feet for 2 years all gone, just residual little lumps on scalp, couple of ridged crumbly nails,
then LS set in.
Osteoarthritis of lower spine, nowhere else so far.
Angina ( surely unconnected).
I have never been a great drinker but do occasionally.
Used to smoke gave it up around same time as got the LS. Am sure no smoking connection as both smokers and non smokers get it!
I got the LP, LS and arthritis ( auto-immune) all within several years of giving up HRT.
I have been slightly overweight all my life, more so recently and dieting is making little difference. I shall ask to get thyroid checked out as apparently 3 out of 10 LS suffers have underactive thyroids.( auto-immune ).
I am basically able to control stress quite well, being calm by nature though maybe I just suppress it, but who cares 
,and now on beta-blockers to boot. Had lots of family stress nevertheless but that was ongoing and I don't think connected to LS onset.. I believe that too much stress does affect our minds and bodies in many ways so no doubt can make LS worse, why not?.
Over the years, like all of us, I have kept my ears to the ground for possible pointers as to causes.
Many of us have suspected stress and diet make it worse. I personally , taking all into account that I have read, don't see that diet in itself makes any difference to LS, but I think if you feel better in yourself for cutting things out or introducing things then it does good in its own way, might even have a placebo effect. In that sense I am all for diet changes which are beneficial anyway, e.g. low sugar et
A more than co-incidental genetic link !.
A credible hormonal link to onset of LS, re HRT, re menopause starting/stopping, re pregnancies, re onset of adolescence( this can halt it)..
Possibly too there are different causes - and links to insect bites in some parts of the world, so insects carrying some micro-organisms. this has been mentioned a few times but not a strong link. Ticks have been suspect.
I'd like to know if dog owners' incidence of LS is higher than non dog-owners. might be nothing in it of course. Another straw to grasp.
As LS seems to be too rare to get much attention from the medical world, also of course not forgetting relatively fewer men get it, so it is considered mainly as just a women's disease, 
and yes, that discrimination does still exist, I think it is really in our own hands to try to find out the links ourselves.
Any other observations would be gratefully received and devoured thanks.