rooted

You can see it positive, but also negative. For example...
First these twins are human lab rats. We don't know enough of the process to ensure their health. Taking away that gen (that prevents HIV from attacking the system) makes them voulnerable to other diseases. We know this from many people who don't have this gen. But those people got so on a natural way.
Second. Is this something what will devide the world a lot more? People who can affort it will modify their baby's in their benefit. This will make them "better" than "normal" people, and they may believe that too. We all know what happens when people think they are better than others.
Third. Should we even do this? Don't we first need to find out what the effect will be on the long term. These changes will also be present in their children. They have children with others also with modified dna. We don't know how these will mix. What will become of them? Will they still be human?
What with the mistakes the gen programmers will make? We all know programmers or far from perfect.

Just a thought.
It's one person making the choice for the world to do this. Now the genie is out of the bottle. The debate has gotten useless.
I don't care much, too old to be able to profit from it(I'm born since a while). And by the time there could be problems because of it I'll be sleeping under the ground.
Cheers.