So you get a resistance to HIV and a greater level of intelligence? I'm not seeing any downsides yet, though I do recall them saying it would make them more vulnerable to some sort of illness, but I can't remember what.
I don't know why people are so scared about improving the human race. We should be trying (carefully, and with lots of testing and quadruple-checking) to make ourselves better than we are now. We're gonna need it.
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Clearly you've never had a loved one suffer from cancer, HIV, etc. or you wouldn't be wishing it on anyone.