The key to research is picking a topic that is neither too broad nor too narrow. Genetic engineering is a huge topic. Narrowing that down to GMO's, for example, is better but that is still too big. What about GMO's? What would your research questions be?
Let's take a sample topic: cloning. How do we narrow that down? Animal cloning? If your project is longer you could explore several options within animal cloning: bioethics, government regulation, health and safety. If it is a shorter project there is no way to cover all of those pieces and so you would pick one of those subtopics.