Is Electromagnetic Hypersensitivity hereditary?

I don't think so. I think it is acquired via long time exposure to EMF

No, but you might enherit some heavy metals or toxins from Your mother, and by that way maybe Your risk might be higher. Or yoy might learn bad food or technology habits from Your family which increase your risk. Or You might be infected with parasites from your family, and by having parasites theres a risk that your risk is higher.

Me baso en mi respuesta a un extracto de una reciente sentencia del Tribunal Superior de Justicia de Aragón (región española) al que se le reconoce EHS como ACCIDENTE LABORAL: ...."trabajadores especialmente predispuestos pueden resultar afectados por niveles de exposición inferiores de los que recoge la normativa que se basan en los estudios de afectación de la población, tomando como valores medios y sin contemplar PERSONAS ESPECIALMENTE SENSIBLES

I think it is likely very strongly correlated with genetics. Neanderthals may well have parted Africa 1 000 000 years ago. They are not a different species to Cro magnum. That is a racist myth. It takes 4 million years to become un-interbreadable. Probably 2 million years ago our common ancestor had white skin and was hairy. We developed black skin when we lost our hairs. In equatorial sun with sun watts at 1000W/m/m we had UV penetrations that were deep enough to need deep melanin and surface melanin shielding of skin. As Neanderthals went north and settled in Europe they lost the need for deep melanin as they was not any where near as much UV watts that penetrated deep. Because of much more available water, sweating in hot weather became an adequate way to cool and short nm sunshine. Sweat is great at shorting rads. Melanin is also the most conductive organic substance known. More expensive than gold too. Melanin production evolved to increase in nm sunshine rads. Sadly as we wear clothes now we have very little melanin in the areas of skin most prone to surface cancers too. Brest.
I think that ES can most easily be explained by the inheritance of a relatively random spread of melanin shielding on our skin sensors. For those of Neanderthal skin genetic decent the melanin has not been necessary for a million years. It is claimed now that 5% of white Europeans genes are Neanderthal. These sensors initiate skin distress. They form part of the neuron-endocrine system. These are designed to be activated rarely, locally and short term. Now RFRs from wifi phones etc are shorting out in this dermal layer 1-3mm inside our skin. This is as much as 24/7 often. This shorting simulates extreme all over body stress in our primordial defense signaling system. Our conscious brain is largely unaware of this signaling as it evolved separately. This auto non over-ridable self defense. You cannot stop blood clotting by thinking about it. Or pain or sweating. We do these things automatically without thought. Many peoples exposure is so extensive that they have forgotten what it is like not to be in rads. Those without melanin shielding will have any one or more of the endocrine system disruption illnesses that have become epidemic since the GSM networks started and get worse annually. AM radio signals can do this too as I know only too well. ES is the tip of the iceberg.

The genetics that make some of us more vulnerable are inherited traits but it takes a trigger to activate a gene in a negative way. IMMERSING OUR WORLD IN MANY FORMS OF IT HAS BROUGHT IT TO LIGHT.