A child born abroad to one U.S. citizen parent and one alien parent acquires U.S. citizenship at birth under Section 301(g) INA provided the citizen parent was physically present in the U.S. 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 are required for physical presence in the U.S. to transmit U.S. citizenship to the child.
However a foreign national gives birth on US SOIL and bingo US CITAZEN is born! SIC
“...five after the age of fourteen are required for physical presence in the U.S. to transmit U.S. citizenship to the child.”
People have always been saying that Anne fell short of this by almost 5 months. But if this document is not a forgery and he was born in Kenya, Anne must have fallen short by several months more since her “physical presence” was not in the U.S.