I think there is a real difference between being averagely intelligent and being stupid.
I always thinks stupid means someone who is culpably ignorant, who should, as they say, 'know better'. I have a mildly learning disabled friend, I would never describe her as stupid, because within her limitations she is thoughtful and listens and acts on advice given her by those she trusts.
This is what AMN has never done. We had friends in the navy where he was considered arrogant and unwilling to listen to advice or takeit, unless compelled to. I say this with no disrespect to his courage shown in the Falklands War.
This has been his problem all along, not that he is not as bright as his siblings, but that he ispig headed and unwilling to take advice from anyone.
Even after that car crash of an interview with Emily Maitlis, he cannot see how he is his own worst enemy and should be prepared to take advice and be apologetic. let alone continuing to stand by everything he said in that interview, when it has been proven without doubt that it was not true.
Unfortunately he chose a wife who may be brighter but is still eually, if not more, stupid