That may have been the law in 1961, but current law says "a person born, after December 23, 1952, outside the United States and out of wedlock shall be held to have acquired at birth the nationality status of his mother, if the mother had the nationality of the United States at the time of such persons birth, and if the mother had previously been physically present in the United States or one of its outlying possessions for a continuous period of one year."
US CODE TITLE 8 > CHAPTER 12 > SUBCHAPTER III > Part I > § 1409, Children born out of wedlock
Now if there was a change in the law from 1961 to present, I wonder what actions a person would have to take to make his citizenship retroactive to birth??