Citizenship of the United States
A person who is considered a citizen by more than one nation has "dual citizenship". It is possible for a United States citizen to have dual citizenship; this can be achieved in various ways, such as by birth in the United States to a parent who is a citizen of a foreign country (or in certain circumstances the foreign nationality may be transmitted even by a grandparent) by birth in another country to a parent(s) who is/are a United States citizen/s, or by having parents who are citizens of different countries. Anyone who becomes a naturalized U.S. citizen is required to renounce any prior "allegiance" to other countries during the naturalization ceremony; however, this renunciation of allegiance renunciation of citizenship to those countries.
Surrogacy
The citizenship and legal status of the children resulting from surrogacy arrangements can be problematic. The Hague Conference Permanent Bureau identified the question of citizenship of these children as a "pressing problem" in the Permanent Bureau 2014 Study (Hague Conference Permanent
Bureau, 2014a: 84-94). According to U.S. Department of State, Bureau of Consular Affairs, for the child to be a U.S. citizen one or both of the child's genetic parents must be a U.S. citizen. In other words, the only way for the child to acquire U.S. citizenship automatically at birth is if he/she is the biological son or daughter of a U.S. citizen. Further, in some countries, the child will not be a citizen of the country in which he/she is born because the surrogate mother is not legally the parent of said child. This could result in a child being born without citizenship.