All of these men were involved in the school of thought known as Eugenics. This idea focuses on breeding individuals within a society that have highly desirable characteristics. Ultimately, the goal was to improve a society by only having individuals with the best characteristics reproduce.
These three individuals all studied this school of thought in one way or another.
Dugdale studied criminal history and genetics in order to see if there was a genetic explanation as to why some people ended up as criminals.
Estabrook used Dugdale's studied and reanalyzed the data to come up with a concept that focuses on how hereditary traits played a more critical role in developing criminals in comparison to environment.