Re family connection, In one wing of my family, my fathers side, my dad had a CF/S, very different to mine as no immune symptoms but would meet some criteria, his brother RA, his sister sjogrens, me his daughter ME and my cousin, daughter of mother with sjogrens, lupus. I got significantly sick in my teens as did my cousin though we have different illness, that’s quite rare. We hardly saw my cousin or aunt but genetically, looks/interests I’m very similar to my cousin. I think that the family connection being genetic is pretty strong. In families where multiple children or parent child get it it would make sense if all ate poorly or got same infection but if they didn’t and got Ill at different years I think that likely be biological cause unless you’re blinded by psychological interpretations to these type illnesses as some are. Even if deprivation or stress potentially contributes to poor outcomes within a family, lots of people have deprivation and stress and don’t get severe chronic, physical illness, fortunately.
By physical illness I mean physical symptoms, muscle exhaustion, muscle pain, neurological pain, temperature control issues, nausea and headaches, flu symptoms etc. I think it’s right to call and defend ME as physical and if you don’t you allow psychological or behavioral interpretation to persist. ME doesn’t present as mood or behaviour disorder so AFAIC it’s not psychiatric, it does present with many sickness symptoms. Afaic my illness is as physical as my relatives and more debilitating and it’s helpful to assert that. If my cousin with lupus started saying the use of the distinguishing term was meaningless for her illness I’d think it odd and it seems only in CFS that there’s a call for removal of distinction. Psychiatric illnesses might have a brain or inflammation basis but they present chiefly with mood or behaviour disturbance don’t they, OCD seems to me very different to FM even if brain issues ultimately cause both. Obviously psychiatry and neurology have over Lap but I think that the distinction in presentation for most conditions is useful. With severe ME, if I was in a flare and I had to go to hospital it would be entirely inappropriate to put me in a mental hospital, if I had severe schizophrenia or psychosis and was in a flare up it would be inappropriate to put me in a general hospital.
As there’s the connection, as I’ve suggested in my own family, with other illness groups that’s also important as I think that there’s established family association/increased chance in those.