A Tri-Channel Framework of Intergenerational Transmission: Germline, Epigenetic, and Somatic-State–Mediated Environmental Inheritance

Classical genetics attributes intergenerational inheritance primarily to germline genetic variation, while contemporary biology has expanded this view to include epigenetic mechanisms. However, a large class of robust, empirically observed parent–offspring influences remains theoretically under-integrated: the systematic impact of parental somatic states on offspring development via environmental mediation, including education, resource allocation, cultural practices, and developmental niches. In this paper, we propose a Tri-Channel Intergenerational Transmission Framework that unifies (i) germline genetic inheritance, (ii) epigenetic regulatory inheritance, and (iii) somatic-state–mediated environmental transmission within a single conceptual and semi-formal structure. Crucially, the third channel does not posit the biological inheritance of somatic mutations, but rather models how somatic states—shaped by somatic genetic variation, development, injury, learning, and aging—function as endogenous generators of offspring developmental environments. We argue that this framework clarifies conceptual confusions surrounding non-genetic inheritance, avoids Lamarckian misinterpretations, and provides a principled extension to existing evolutionary and developmental theories, including Developmental Systems Theory, niche construction, and Extended Evolutionary Synthesis. We further present a weakly formalized dynamical model capturing how somatic-state–dependent environmental mediation systematically alters developmental trajectories across generations.