Yes, I’ve read the book. It’s hard having one child with SZA, much less 6! Genetics is a complicated topic. The parents did not have mental illness and yet half of their children did. I think it’s possible to have a genetic disposition to mental illness as it’s possible to have genetic link to other diseases. The closer the relationship - probably the more likely one’s medical history/outcome is linked - but not always. There is no way to know IF one will develop a certain chronic illness. I’m sure lots of factors are “at play” to determine the outcome. Saw other poster on this site who said her grandparent’s three children were all SZ. Neither grandparent was ill nor the grandchild that posted.