Metaphorically and analogy wise: If you think as genes as the holes on a flute, gene expression as the music then environment is what determines "bad" music. But there is no one specific gene that is known or corellated specifically for adhd symptoms.
ADHD is likely genetically caused but the genes are in everyone just expressed in specific environmental circumstances impossible to know for sure in a lab(cause they mostly look at outward behavior in lab settings and fmri blood flow).
But I've been doing meditation(45mins 3-4 days a week) I've also learnt for myself that 30 mins of power naps does wonders for my mind. The medication's effectiveness AND gated on the former two; SNRI, Dopamine reuptake inhibition is like carpet bombing and only makes you ready for rewiring: you still need to rewire with therapeutic and Behavior Therapy techniques.
But I know for a fact that my brain waves are different on days I do meditation and power naps.
I really do want to know if deep brain neural activity detection data can detect bad waves and possibly close the loop by providing corrective waves.
Alternatively, it can be chemically shutdown/reset, the basic principle of neuroleptics. That is a coarser action though. When things hit the fan. Not nearly as much as the usual recommendations from clinicians.
For ADHD, they prescribe stimulants which make sense if we consider that the brain is searching for triggers of dopamine.
Some other conditions seem to require the opposite but this has a lot of side effects.
I think that in fact, the dopamine modulation require more fine grained handling and this is two sides of a same coin.