While ethics and practicalities may have an influence on a sociolog’s decision about a topic, as well as their theoretical perspective, there are other factors that can also impact this choice.
Sociologists are often influenced by personal interests when choosing the subject matter they will research. Usually, they will have identified a problem or sociologytopics.com social phenomenon in which they have an interest. Durkheim had a close friend who took his own life and it played a role in him choosing the subject.
This links to the theoretical perspective. Marxist sociologists may want to investigate topics that relate to social class, or problems with capitalism. Feminists might be more interested in gender topics, etc.
Funding is an important factor. Research on sociology is funded often by academic funding organisations such as ESRC or non-governmental organisations that have a special interest in a particular social problem. Sometimes, it is even sponsored by the industry. These organisations will fund some topics if they get a return. Lung research, for instance, will often struggle to secure financial support due to the long wait time required by funding bodies to publish the results. Research into subjects that align with the company’s interests and aims is unlikely to be funded by an NGO.
Another factor that is important is the availability of opportunities. An opportunity will lead a researcher to choose a particular sociological subject. Venkatesh studied gangs living in Chicago’s housing project (estates) because they were near the university where Venkatesh was a student.