 With the onset of the molecular revolution in biology in the 1950s and 1960s, the suite of services that medical geneticists could offer patients expanded. Carrier screening became available, which allowed for informing a patient that they carried a recessive allele of a disease-causing gene and so may pass that trait onto a child even if they did not show symptoms of the disease themselves. Amniocentesis was also developed, which allowed for extracting fetal cells from the amniotic sac, culturing those cells, and then testing for a range of medical conditions in the fetus (Harper 2008).