Biographising the Bard

I watched a recording last night of Ethan Hawke's largely bland investigation of Macbeth in the intermittently arresting series, My Shakespeare. One nugget of criticism did however stick with me. That nugget came from Dr Gwen Adshead, a psychiatrist working at Broadmoor who observed that Macbeth's language in the immediate aftermath of Duncan's murder becomes fractured just as is the case with the real killers with whom she has worked. This observation put me in mind of Walter Bagehot's certain assertion (in the context of a hunting passage in Venus and Adonis) that one can tell a good deal about Shakespeare from his works,

It is absurd, by the way, to say we know nothing about the man who wrote that; we know that he had been after a hare.

But is that right? Can we really construct a picture of what Shakespeare must have been like merely by reading his works. Taking Bagehot's logic to an extreme (and taking also Dr Adshead to be right) are we to assume that Shakespeare had direct experience of murder? Maybe he was just a bloody genius, a bloody big genius. Does it matter even a jot what Shakespeare was like - or are the plays the thing?

I had haggis for tea today. Which was nice. So far as I can tell the word 'haggis' does not appear anywhere in the complete works.