The American journalist Sally Herships has long felt she carries within herself a sense of the trauma suffered by her grandmother a century ago, in Russia, and subsequently passed down through her own mother.How is it possible to explain a fear that isn't of any thing tangible or present, a fear that isn't our own, that isn't rooted in direct experience? Psychiatrists know that behaviour can condition how we feel with physically-measurable impact - for example, upon the PAG o