I can believe that Andrea Yates was convicted of murdering her children. What I can't believe is how quickly the jury made its decision. It took them less than four hours, after a three-week trial. Certainly Texas law made an insanity defense difficult (and Yates' actions made any other defense impossible), but I would have thought that the jury would have debated the issue for longer than it took them to decide what to have for lunch. It will be interesting to see what happens in the penalty phase of the trial, where Yates' mental illness (which both the prosecution and defense agreed existed) can be a mitigating factor.
As Damian Penny points out, there's a huge difference in the approach to defendants who are fathers and defendants who are mothers. There's a presumption that (as Yates' attorney argued), "If drowning five children by a loving mother isn't a gross psychosis, there isn't any such thing as gross psychosis," while a man who does the same is just evil.