Arcanewireless, here is the dog food post for your delectation.
I was being serious about Harry eating cat food, as you can probably tell, context wise..... 
'I think most parents would find it wrong, on a parenting forum, for one child to be treated more favourably and be given more just because they were born first.'
So what are we saying? That Harry, despite his incredibly privileged upbringing, his expensive schooling at an elite establishment, the role in the army he would never have had access to without his background, the covering up of misdemeanours which would have seen a person from a less privileged background sacked, the opportunities for travel etc, etc that he feels hard done by because he won't be king?
Has he really been treated any differently as a member of the family? William has a role to play. If Harry had stayed within the 'royal' bit of the family, he would have had the large apartment at Kensington Palace, the nice country house, the staff, the social occasions. But he decided it wasn't for him and left. So why feel hard done by? You make it sound as if William was living in a palace feasting on lobster while Harry slummed it in a garden shed, eating cat food out of a tin.