Why did later scholars discredit many of the positive school’s claims about inherited criminal traits?

Later scholars largely discredited the claims of the positive school regarding inherited criminal traits because the alleged facts supporting these theories were found to be scientifically unsound.1

The positive school, led by Cesare Lombroso, posited that criminals were "born" with specific physical and mental anomalies—atavistic "stigmata"—that doomed them to a criminal career. However, as the field of criminology advanced, these assertions were rejected in favor of environmental factors. Key reasons for this shift included:12

• Lack of Rigorous Data: Early researchers lacked the tools to study heredity directly, relying instead on controversial measurements of physical features like skull size or facial angles to infer personality traits.3
• Complexity of Causation: Scholars increasingly recognized that human behavior is influenced by a complex interplay of genetic and environmental factors, rather than rigid biological determinism.34
• Scientific Advancement: The rise of modern genetics and genomics demonstrated that genes are not destiny; even in cases with a clear genetic basis, environmental conditions play a significant role in how traits are expressed.3

Ultimately, while the positive school’s specific biological claims were discredited, it left a lasting legacy by shifting the focus toward the individualization of treatment and the scientific study of the criminal.12