Date of birth, if twins are born, the date of birth shall prevail, so there are also brothers and sisters, and twins are brother and sister. These are all normal questions. In other cases, the relationship between brothers and sisters, brothers and sisters, is nothing special in theory. Twins born near time may or may not be born at the same time. Because every hour is two hours, and the time difference between the birth of twins may be exactly within one hour, or another hour, which may or may not exist at the same time, which is easy to understand.