> Also, bipolar disorder is the _only_ mental illness in which a genetic
> factor has been detected. That does NOT (Repeat, NOT) mean it is
> "inherited" or "genetic." Probably Miles could word this more precisely
> than I can.
>
Well, twin and adoption studies do support the idea that genetic factors, under certain environmental conditions, can increase the likelihood of developing bipolar disorder. However, this statement is true of a few other clinical syndromes too:
schizophrenia depression anxiety disorders (e.g., panic disorder)
It is true that the heritability ratio for bipolar is higher than the heritability ratio for these other disorders, so that may be the original basis for Carrol's claim.
Miles