19 世纪未期，一些具有美国土生华人身份的美国公民陆续回到中国故乡，探望久别的双亲，娶妻成家，制造“海外出生的子女”。这些回到五邑的华人，再返回美国去，就要向移民部门备案，报告自己在家乡生了一个孩子，从而获得一张美国政府发给的“出世纸”。有些逗留超过一年的，甚至会申报自己生了两个孩子。
依照出世纸，在美国的华侨可以在十多年后按照正常程序，将自己在中国家乡的儿子或者是别人的男孩，合法地移民美国。
为什么是男孩？因为按照中国传统的观念，男孩子要出国打工赚钱，女孩子要留在家中。
事实上，很多华人离开家乡返回美国时，孩子还没有出生，有的妻子甚至根本没有怀孕。但是，利用这张出世纸，可以将兄弟亲戚的儿子办理移民，有的还可卖给别人，赚一笔钱。
所以利用出世纸移民美国的，大多数并不都是真实的父子关系，有的是卖纸冒名顶替的移民。
不管是否真实，通过出世纸移民来美国的，被俗称为“纸生仔”，而冒名顶替的假儿子则被称为“纸面儿子”。
At the end of the 19th century, some American Chinese embarked on a root-seeking journey back to visit their homeland, visiting their parents and forming local families. Upon their return to the U.S., they should report to immigration authority on the new children born abroad, then they would be issued with a birth certificate recognized by the government. Some of them who had stayed in China for more than one year even acclaimed that they had two babies born into his family. According to U.S. laws, such Chinese boys were entitled to emigrate to the U.S. about 10 years later in light of Birth Certificate. Tradition-ally, only boys should make money outside while girls should stay for family chores.
However, the story did not as simple as it appeared to be. Some helped the sons of their relatives to emigrate to U.S. by “legal” Birth Certificate, or sold it for money, which brought a lot of doubts to the identities of Chinese immigrants based on birth certificate. Those who were permitted to be given the birth Certificate were called “Zhishengzai” (paper-born boys), among whom the false children were called “Zhimian Erzi” (Paper Son).