But there are limits to what genes can express, based on the cell's capabilities. For instance, you could make someone a wolfman by adding hair, but you couldn't have them grow leaves like the Jolly Green Giant. Our cells just don't have the kernel level support or whatever you want to call it.
We share half our genes with the banana. Granted the scientists are (probably) only talking about editing the 0.3% of the genome that makes humans different from each other, but with so much of our DNA shared with other eukaryote celled life, adding leaves may not be that difficult.
