When I was 'interrogated' on arrival, they weren't interested in flying on a tourist visa but concerned that my true intent might be to stay and become another illegal immigrant.
There are plenty of Brit and other bums living and working illegally in the U.S.A. so their concern is valid hence you were asked for 'sufficient information concerning my ties to the UK'.
As was suggested, attempt to prove that you have roots (business, children, job, house etc.), which mean that you want/need to return, but I wouldn't send them a copy of your membership of a militia or mosque !