Adults have a small chance of acquiring those traits too. Due to selection effects adults that don't have traits have a much lower probability than a fresh new baby of turning out this way.
As well as, of course, as having far less malleable minds that have yet to crystallize the habits their upbringing gives them.
Are you ok with babies with very low probabilities of getting such traits being killed?
Far less averse, particularly in an environment where negative externalities cannot be easily prevented. Mind you I would still oppose legalization of killing people (whether babies or adults) just because they are Jerks. Not because of the value of the Jerks themselves (which is offset by their effects on others) but because it isn't just Jerks that would be killed. I don't want other people to have the right to choose who lives and who dies and I'm willing to waive that right myself by way of cooperation in order to see it happen.
A few notes about the site mechanics
A few notes about the community
If English is not your first language, don't let that make you afraid to post or comment. You can get English help on Discussion- or Main-level posts by sending a PM to one of the following users (use the "send message" link on the upper right of their user page). Either put the text of the post in the PM, or just say that you'd like English help and you'll get a response with an email address.
* Normal_Anomaly
* Randaly
* shokwave
* Barry Cotter
A note for theists: you will find the Less Wrong community to be predominantly atheist, though not completely so, and most of us are genuinely respectful of religious people who keep the usual community norms. It's worth saying that we might think religion is off-topic in some places where you think it's on-topic, so be thoughtful about where and how you start explicitly talking about it; some of us are happy to talk about religion, some of us aren't interested. Bear in mind that many of us really, truly have given full consideration to theistic claims and found them to be false, so starting with the most common arguments is pretty likely just to annoy people. Anyhow, it's absolutely OK to mention that you're religious in your welcome post and to invite a discussion there.
A list of some posts that are pretty awesome
I recommend the major sequences to everybody, but I realize how daunting they look at first. So for purposes of immediate gratification, the following posts are particularly interesting/illuminating/provocative and don't require any previous reading:
More suggestions are welcome! Or just check out the top-rated posts from the history of Less Wrong. Most posts at +50 or more are well worth your time.
Welcome to Less Wrong, and we look forward to hearing from you throughout the site.
(Note from orthonormal: MBlume and other contributors wrote the original version of this welcome message, and I've stolen heavily from it.)