According to the author, which of the following is NOT an achievement of the 20th century science?

Bidding farewell to the century of physics, the one in which we split the atom and turned silicon into computing power. It’ s time to ring in the century of biotechnology. Just as the discovery of the electron in 1897 was a seminal event for the 20th century, the seeds for the 21st century were spawned in 1953, when James Watson blurted out to Francis Crick that four nucleic acids could pair to form the self-copying code of a DNA molecule. Now we re just a few years away from one of the most important breakthroughs of all time: deciphering the human genome, the 100,000 genes encoded by 3 billion chemical pairs in our DNA.
   Before this century, medicine consisted mainly of amputation saws, morphine and crude remedies that were about as effective as bloodletting. The flu epidemic of 1918 killed as many people (more than 20 million) in just a few months as perished in four years of World War I. Since then, antibiotics have allowed us to vanquish entire classes of diseases. As a result, life expectancy in the U. S. jumped from about 47 years at the beginning of the century to 76 now.
   But 20th century medicine did little to increase the natural life-span of healthy humans. The next medical revolution will change that. Because genetic engineering has the potential to conquer cancer, grow new blood vessels in the heart, block the growth of blood vessels in tumors, create new organs from cells and perhaps even reset the primeval genetic coding that cause cells to age.
   Our children may be able (I hope, I fear) to choose their kids’ traits: to select their gender and eye color perhaps to linker with their IQs, personalities and athletic abilities. They could clone themselves, or one of their kids, or a celebrity they admire, or maybe even us after we’ ve died.