The idea of chromosomes and genes as causal agents in development and heredity originated in late 19th-century cytology, and it was most strongly supported by Theodor Boveri and Edmund B. Wilson. The concept of genes, which was central and most fruitful in classical genetics, appeared, however, unappealing and insufficient to many for explaining complex biological phenomena such as development. Philosophical outlooks, among them “Lamarckian” and holistic predilections, played a significant role in scientists’ objection to genes as causal factors. A wide conceptual gap between genetics and developmental biology ensued. The strongest attack on the concept of genes was launched by agronomist and politician Trofim Lysenko in the Soviet Union under Stalin. Brushing aside the “Mendelist-Morganist” methods of classical genetics, Lysenko put forward a holistic concept of heredity that incorporated development and heritable responses to environmental conditions, similar to Darwin’s Pangenesis theory, though of course some 60 years later. Recent developments include the role of genes in research on epigenetic marks and in systems approaches based on embryological gene regulatory networks.