It's a tricky one. Personally, I think we ought to broaden our definition of intelligence to include things like humour, empathy and love of beauty. We've all met people who excel at logic and mathematics yet fail to get a joke or pick up on someone's feelings. And we've all known people who are clever, with a string of qualifications, yet feel nothing when they walk around an art gallery or watch the snow fall.
Even within academia there are types of intelligence. I studied art history at university, and it was funny to walk through the economics department then the literature and art department. The economics professors were often nerdy little men with bow ties. One, I remember, looked like something out of a bad Hollywood comedy, with trousers that were too short for him and a funny little walk. Then you'd get to the art department and the lecturers would be dressed like characters out of Oscar Wilde or Withnail and I! OK, those are crude stereotypes, but you get my point.
My brother is a good example of how difficult it can be to pin intelligence down. He was hopeless at maths and science (I don't think he even turned up to his maths GCSE), yet he excelled at literature and was reading Aldous Huxley and George Orwell as a teenager. Today, his house overflows with books on Shakespeare and Chaucer and so on. Ask him to use a laptop, however, and he's helpless.
The key is to identify their passion. The child has to love a subject, or forget it. I have known very, very intelligent people with zero academic leaning. They are clever, but there is no particular subject that captivates them. If you want to raise an 'academic' child, inspire them with a love for something. Take them to art galleries, museums, bookshops, plays, etc, and wait. Something might just light the fuse. Brian Cox, for example, said it was watching Carl Sagan's Cosmos on TV. I know someone who is doing a PhD in Latin who swears he would not be where he is had he not watched I Claudius as a child. And I once read an interview with a philosopher who traced his career back to reading A Hitchhiker's Guide as a boy.