To state that EDs are a “brain disorder“, and thus, by apparent extension, proceed forward to the additional assertion that experience and environmental factors ( such as parenting, as a pertinent example) can play no role in the disorder’s development, may be an example of drawing unwarranted conclusions. I suspect that any " new school" psychologist or neuroscientist worth his salt would support, with little hesitation, the statement that experience and environmental factors can and do produce significant physical changes in brain structure. Changes in structure that may tip the scale, in combination with other admitted factors such as genetics, and result in expressed psychological conditions that could also be properly labeled as “brain disorders.”
For example, it’s been conclusively demonstrated that psychological trauma and abuse correlate with quite substantial and measurable structural changes in the hippocampus and amigdala , changes that are (admittedly, also by extension) thought by many to underlie the pathological symptoms of PTSD, a condition that as most would agree, might also be labeled a “brain disorder.”
And while it's confoundingly true that EDs often show up in the families of good parents, EDs remain mysterious, and to then proceed to the conclusion that parenting, no matter what it's form, could have no possible effect on the development of EDs remains akin to the argument that since many trauma victims do not go on to have PTSD, experienced trauma can play no possible role in the development of those who do, and that's it's existence in a victim's background is a mere and unrelated artifact of coincidence.
To close, I suspect that most neuroscientists would agree that simply labeling a current condition a “brain disorder” does not, by extension, preclude the very real influence of environmental factors on the disorder’s development. And that the drawing of such conclusions, no matter what comfort they may provide to honestly and authentically good and caring parents ( or to others who, in truth, may not be that good ) is by all current scientific accounts and standards, unwarranted.