Do not ask if it is common. Ask if it is possible.
At the time of the archiving of the PJ investigation all possibiles were still open;
Despite all of this, it was not possible to obtain any piece of evidence that would allow for a medium man, under the light of the criteria of logics, of normality and of the general rules of experience, to formulate any lucid, sensate, serious and honest conclusion about the circumstances under which the child was removed from the apartment (whether dead or alive, whether killed in a neglectful homicide or an intended homicide, whether the victim of a targeted abduction or an opportunistic abduction), nor even to produce a consistent prognosis about her destiny and inclusively - the most dramatic - to establish whether she is still alive or if she is dead, as seems more likely.
http://www.mccannpjfiles.co.uk/PJ/LEGAL_SUMMARY.htmDespite this, you have decided, based on your 'system analysis' that the parents can be excluded from suspicion. It would be most interesting to know how that works?