persons acquiring citizenship by method (2) are called british citizens "by descent"; those acquiring citizenship by methods (1), (3) or (5) are called british citizens "otherwise than by descent". british citizens by registration, method (4), may be either, depending on the circumstances. only citizens "otherwise than by descent" can pass on their citizenship to their children born outside the uk or a british overseas territory automatically; british citizens "by descent" can pass on citizenship to their non-uk born children only by meeting certain uk residence requirements and registering them before the age of 18.