Computer simulations provide students the opportunity to observe and interact in realistic biological experiences. This designed simulation, “The Trio of Genetic Diversity,” made it easier for students to grasp the reasons for genetic diversity. During and after meiosis, the three processes (crossing over, independent assortment, and random fertilization) that occur are the primary sources of diversity. A separate module was designed for each of the three processes and presented in the order of occurrence. It will take three to five minutes for student to try each module. The simulation in this study was developed using Java programming language in the NetBeans IDE 8.2 development environment, along with the Swing GUI module. Java was used in the simulation so that it can be run easily in almost every operating system; furthermore, the interface is included in the Java library. The NetBeans IDE 8.2 software allowed the simulations to show the range of possibilities for genetic diversity. Chromosome images were created and converted into a transparent structure, and the coding process was started. The images and button actions in the simulation interface were carefully designed so that the user could understand them easily. This article introduces the simulation program and its features.