When your mother - in this case diana - has SO many illicit affairs - it is a natural reaction for people to question paternity. If for example smurfy you found yourself subject of a paternity claim from the local bike you would say "hey but who HASN'T she done?" And you would be in your rights to do so. Of course there may well be likenesses of BOTH families in ALL children. Just seems, considering the timing and unfortunate appearance, that Harry MAY be of of differing parentage to his brother...