It's not always a crime necessarily but harming people to get what one wants is usually a crime. As for constraining human behavior there's really only two tools, benefit the behaviors you want and punish the ones you don't want. People will obviously be self interested and will sometimes cause a lot of harm to get what they want but they wouldn't if they knew for a fact they would be caught and punished. It's more so the likelihood of being caught than the punishment that's actually the deterrent. You can have an extreme punishment for something but if it's unlikely someone will be caught then they will take their chances. Downside is with a higher rate of catching bad behaviors we diminish privacy. An extreme would everyone being watched and recorded 24/7 would make it trivial to catch any bad behavior or crime but there would be zero privacy.

As for Gattaca,. I think it's more so that they used it to differentiate society into two groups where one was treated very poorly more so than the gene editing itself being the issue. For sure we will cure genetic diseases and then move into grey area stuff like giving people perfect eyesight and so on. I think it'll be far too tempering to make designer babies though, higher IQ, better looking (subjective), better physique, better health and so on. Of course anyone who's ever bred animals knows you can breed them to constrain their behavior so one could theoretically alter humanity to be more compassionate and less of a jerk to itself.