Introducing new genetic tools could cause either an intentionally malicious or an unexpected White Plague, resulting in massive loss of life. Biological warfare/ terrorism could take on a terrifying new level, with these white plagues and other modified diseases known as Chimeras(think of super-anthrax, or a super influenza, resistant to all antibiotics) having the ability to decimate the entire world's population in a short amount of time. Terrorists, or even entire countries under mad men like Saddam Hussein could release a disease that has much stronger consequences than they had originally intended. Something small could have the possibility of ending life on Earth.
On a different level, it poses a threat to the environment. Much like non-native species easily take over in new environments, GE plants and animals could decimate the environment and disrupt the food chain, causing slower-acting but still incredibly long lasting negative effects.
In addition, cloning threatens our political system in terms of equality, a power imbalance, loss of individuality, loss of human rights and freedoms, and many other unpredictable changes. Like in the movie "Gattaca", humans that aren't genetically cloned with certain superior traits could be discriminated against. Only humans with genetically perfect DNA could be allowed to reproduce or work in certain, high-level jobs. This would disrupt our entire economy and employment system. Sports would be a lot more fun because everyone's muscles would allow them all to jump 8 feet in the air, but wars would be a lot less fun for these same reasons.
Genetic engineering would cause a greater gap between wealthy nations and non-wealthy nations. The wealthy nations would have the know-how and technology to make stronger, smarter, superior humans while the other nations would continue to fall further behind.
And one of the saddest parts about
genetic engineering is that it could end individuality. Everyone would
want to be skinny, muscular, beautiful, smart at math and science, and
so on forever. When your DNA can be shaped, who would choose "inferior"
traits? It could possibly end artistic expression and individuality, and
make everyone predictable, indentical, and boring...much like a...."robot".