Are we going to live in a century of choosing our look like or our body type or our intelligence? Can we (or at least our parents!) order our feature before we were born?
Generally, I believe that everything is perfect in the way god has made them, and this world has an equilibrium which we might not understand but it doesn't mean that does not exist. And if we make a little tiny change in one part of the world there will be definitely a reaction in the other part. So, every change in nature has consequences. For example, nowadays we are suffering from global warming problem which is the consequence of our mistakes treating the nature in the industrial revolution. Most of the time because we don't know the long-term effects of our actions we consider it as if it is harmless while on no account could we put the next generation's life in danger.
Genetic engineering is one of the science that instinctively talk about change. The aim of this science is understanding the process of inheritance and try to make changes in order to improve humans life. The very controversial issue is “are we going in the right way or we are fighting the god's rules?”
With no doubt, genetic engineering can help us eradicate diseases such as cancer. Although these changes have been made by our previous mistakes, it would be a cure for all of our sufferings. But, on the other hand, genetic engineering might make human able to change something we shouldn't and only god knows what will happen if we do that. For example, just imagine a world in which every one has a same appearance or a same intelligence. I think it would be boring living in a world in which every things is arranged already.
At the end, I believed that we don't have the knowledge and right to change every thing and to use genetic engineering we should have some red lines and avoid crossing them.