Hi Ed - As it's programmed at the moment, this 'related question' feature is just not working.
As an example have a look at Bob901's question, 'Week in Hand', 16:05 Weds 09th Jan 2013. The 'related questions' shown against his question bear no connection with what Bob was asking. They appear to be just random questions plucked from the bowels of your computer.
I'm not against tweaking AB if it improves the site, but with respect, I think until you get the 'badges' issue sorted out, you should put this new feature on hold.
Kind regards