 By the 20th century, the concept of epigenesis the interaction between a genetic program and environment was established and in the second half of the 20th century researchers had evidence that environmental factors can cause malformations and even trans-generational effects.One of the first environmentally induced congenital malformations in humans were recognized as a result of maternal irradiation.Hiroshima (’53), and Nagasaki (’55), had ascertained this fact for the first time based on the records of births occurring before May 31, 1946, but after the atomic bombing (August 6, 1945, in Hiroshima; August 9th, 1945 in Nagasaki).