Both schizophrenia (SCZ) and bipolar disorder (BD) are enigmas. Scientists have linked hundreds of genes to each of these conditions, but the genes alone seem to only slightly impact the development of the SCZ and BD. For example, an individual with SCZ-associated genes is only 7% more likely to develop the disorder compared to a person without those genes. This, in and of itself, is not unusual. It suggests that genes are necessary for the development of these conditions, but they are not sufficient to cause the conditions.
However, if a person has one of these disorders, there is a 74 to 81% chance that a close family member also has it. In other words, if a person possesses the genes associated with one of these disorders, it doesn’t dramatically increase their chances of developing that disorder. However, if a family member has either SCZ or BD, then their chances of developing that disorder are quite high. And therein lies the enigma: how can a disorder be passed to offspring if not by genes?
Read more at: https://www.freethink.com/health/schizophrenia-bipolar-dark-genome