The idea that the placenta protects the embryo from harmful environmental substances was disproven between 1957-1961 when thousands of children were born with malformed limbs. Just as thalidamide, the causative agent of this malformation, affects a developing child, geneticists also attribute other adverse environmental factors (alcohol, malnutrition, exposures to various occupational hazards) as causative agents of genetic and chromosomal mutations. Consider adverse environmental factors. How would these factors affect the genetic precursors, the gametes, to fertilization? What types of mutations could occur to genes and chromosomes? What type of autosomal dominant and autosomal recessive conditions could result?