German Citizenship by Descent
Those born after January 1, 1975 are Germans if the mother or father is a German citizen.
Special rules exist for those born before 1 July 1993 if only the father is German and is not married to the mother. The father must acknowledge paternity before the child is 23, or acknowledge paternity and marry the mother and the child must declare himself or herself to be a German citizen.
Those born outside Germany to a German parent who was also born outside Germany after 1999 will need to be registered as German citizens within 12 months of birth. An exception applies if the child is stateless.
Those born in Germany and adopted to a foreign country should contact their local German Consulate for clarification of German citizenship.
Persons who are Germans on the basis of descent from a German parent do not have to apply to retain German citizenship by age 23. If they acquire another citizenship at birth, they can usually continue to hold this.