Really it must be admitted that only in England and America is there anybody who knows how to establish the genethliac theme and construct a horoscope.
-- J. K. Huysmans, translated by Keene Wallace, Down There, 1891
It must be said, however, that the Arabs went much beyond the classical doctrines of Ptolemy's Tetrabiblos and added to genethliac astrology, which was concerned with the conjunction of heavenly bodies at the moment of birth, a more popular science of interrogations and elections for every occasion in life.
-- Charles Homer Haskins, The Renaissance of the Twelfth Century, 1955
Genethalic derives from the Greek root genéthli meaning "pertaining to one's birth." It is unrelated to the word gene.