About the 9th week the fetus responds to upsets by flexing its torso and extending its head. (Ornstein, Robert, PhD. The Roots of the Self. p 36. NY: HarperCollins Publishing, 1995.)

Genital formation on the fetus occurs between 9-12th weeks. (Joy, Donald, PhD. The Innate Differences Between Males & Females (Audio). CO: Focus on the Family, 1967.)