Dialectic differences.

  Yorkshire dialect word     : barn
  Generally accepted meaning : child
                              (especially a young child, infant) 	
  Old Norse source word      : barn
                               Same as bairn, which comes from
                               the Old English bearn.  bairn is
                               used as an alternative in some
                               parts of Yorkshire, the other
                               northern counties and Scotland.

From http://www.viking.no/e/england/yorkshire_norse.htm