As these myths are passed from one generation to another, they have become engrained into the views of practising communities across the world, including those in Wales.
Gan fod y mythau hyn yn cael eu trosglwyddo o genhedlaeth i genhedlaeth, maen nhw bellach yn rhan greiddiol o gymunedau sy’n eu harfer ar hyd a lled y byd, gan gynnwys rhai yng Nghymru.