According to information posted at the Department of State website, if Mami was not a U.S. citizen and gave birth to the future slimeball in Mexico, and her assassin husband was a U.S. citizen at the time, the rule is as follows:
Birth Abroad to One Citizen and One Alien Parent in Wedlock
A child born abroad to one U.S. citizen parent and one alien parent acquires U.S. citizenship at birth under Section 301(g) of the INA provided the U.S. citizen parent was physically present in the United States or one of its outlying possessions for the time period required by the law applicable at the time of the child's birth. (For birth on or after November 14, 1986, a period of five years physical presence, two after the age of fourteen, is required. For birth between December 24, 1952 and November 13, 1986, a period of ten years, five after the age of fourteen, is required for physical presence in the United States or one of its outlying possessions to transmit U.S. citizenship to the child.) The U.S. citizen parent must be the genetic or the gestational parent and the legal parent of the child under local law at the time and place of the child’s birth to transmit U.S. citizenship
Regardless of what it says at this website, Days viewers shouldn't hold their breath waiting for the writers to get the legal niceties straight.