For me “How long could I get away with driving like an ABSOLUTE ASSHOLE all the time before I lost my licence or had an accident.” Speed limits, red lights, stop signs… forget them all. Every day I have to drive sensibly and obey the law because without my licence I dont have a job, and every day I see at least one person driving like an absolute moron and I wonder…
We already did this unintentionally during our natural evolution. All we really got out of it were a group of humans who can run slightly faster on average, and a group of humans who can drink milk as adults without shitting themselves.
I imagine the timeframe to get any noticable results would be in the thousands of years, even with deliberate selection for specific genes.