Instilled in interdisciplinary cross-cultural perspectives of mythical, socio-economic, literary, pedagogic and psychoanalytic representations, two archetypal, creative inheritance laws interact as 'twins': Eros (fusion/containment/safety) and Thanatos (division/separation/risk). Hypothesising these 'twin' laws as matrilineal (Eros) and patrilineal (Thanatos), this book explores why cross-cultural forms, including gender traits, are not fixed but are instead influenced by earlier flexible matrilineal forms.