Just go look at the "crimes against children" threads and you'll have your answer.
3-5 children A DAY are murdered by their mother or father. 200 a year by their mother. We act like its so rare and uncommon that this happens, but its not.
It happens all the time. The thing is not all parents have the ability to fabricate stories (like CA) and play the media. Some will just dump their kids in the river or in dumpsters and hope nobody finds them out. The news doesn't cover those stories the same way it does these sensational cases. Look at Jhessye Shockley. How much coverage has she gotten? Not much. They originally thought she just wandered away from home. Not very sensational.
So while there are legitimate stories of children being abducted/murdered by complete strangers that is the exception, not the norm. Now you're already pre-disposed to take a hard look at those closest to the child. And then when they (or the media) blast the inconsistencies our alarms go off. Especially with a mother that admits to being " black out drunk". You'd have to have some pretty low standards of parenthood to think that is acceptable and not suspicious of poor parenting at the very least.
There is a far leap from an alcoholic or






parent to murderer, but the gap closes when you have a family not inclined to talk to LE (for whatever reason) and changing their story.
Plus I think there is a psychology present that if the parents did it, we don't have to worry for our own children's safety or fear the boogeyman because we are "better people and wouldn't do that". It makes it a little easier to sleep at night. If we admit that it CAN happen for no reason by strangers then our sense of safety is challenged.
Meh, I am rambling.