doris fuller 's daughter , natalie , 28 , suffered from bipolar disorder and psychosis , and died when she stepped in front of a train in baltimore , maryland , last month .
the mother and daughter pair had shot to fame in 2004 when they collaborated on a parenting guide based on natalie being totally honest with her mother about whatever she was asked .
in the wake of her death , fuller has written about how her illness , which went undiagnosed until her early , and now fuller has opened up about how natalie 's bipolar disorder and psychosis led to her death .