There comes a point at which even circumstantial evidence becomes so overwhelming that it is accepted as conclusive, e.g. few would dispute fingerprint evidence. No doubt different people differ on when that point is reached: I'm convinced that a 36 year-old mother of eight "apparently feral" children living in unsafe, rented accommodation is in receipt of state benefits, whereas, apparently, others consider it just as likely that she is, for example, the beneficiary of a trust fund. Occam's Razor - ever heard of it?