The author argues that a mother’s physical, mental, and emotional state before and during pregnancy substantially shapes the bodily traits, temperament, and capacities of her children, presenting fetal life as the decisive period for variation. Drawing on decades of case observations, the text offers practical counsel on timing of conception, rest, sexual conduct, imagination, and exertion, and assesses how parental conditions can promote or impair talents, health, and moral tendencies. It treats specific outcomes such as birthmarks, deficient development, artistic and musical ability, jealousy, intemperance, and the father’s indirect influence, and urges maternal responsibility for offspring formation.