If you are an employee, it is likely that you try to be friendly toward other workers and get to know more about their personal lives. Learning more about the interests and the lives of coworkers is a way to build a strong team and to develop a sense of camaraderie among employees.
While you might feel some level of social pressure to share more about your personal life at work, you never have the obligation to do so. In addition to this and perhaps more importantly, if you do share personal details such as your gender identity or sexual orientation, you should never be discriminated against as a result.