Bell was the son of Cecilia Barbara Craigie (1813–1882) and Benjamin Bell (1810–1883), and a great-grandson of Benjamin Bell, considered to be the first Scottish scientific surgeon. In his instruction, Joseph Bell emphasized the importance of close observation in making a diagnosis. To illustrate this, he would often pick a stranger, and by observing him, deduce his occupation and recent activities. These skills caused him to be considered a pioneer in forensic science, (forensic pathology in particular), at a time when science was not yet widely used in criminal investigations.