Saw a need/desire to develop ideas and scientific proof as to why crimes happen. Scientific explanations to crime and proof as to why people commit crimes, grounded in the nature of people and the makeup of people. Assumes distinction between normal and deviant based on scientifically measurable factors outside the immediate control of the individual. Behaviour is the reflection of biological, genetic psychological factors. Individuals are prone to crime based on biological traits. Criminals are born based on their genetic make-up. Supports the negative isms in the world. Break from classical theory: crime is individual choice and free will. Focus on individuals and their genetic differences. Crime is all based on someone"s genetic makeup. Supported bourgeoisie in society looking at the differences and took them as markers where different people were more prone to crime, looking at non-white people, brain function, age, sex. The biological concept that fitness is defined by genes and reproduction.