[quote]Because I think there are some folks in India that worshiped an 8-limbed child as a god, and I wouldn't be surprised if genemodding leads to some future Indian children being intentionally designed to have polymelia.[/quote]
Those folks won't have access to such technology most likely, so the issue is non-existent. However, there is a general line that you can set, there are things there is no foreseeable downside to (i.e. removing disease) and those that there is, i.e. aforementioned arms.

However I don't we're going to get far with this, since from the discord I know of your lite-libertarian/voluntarist philosophy which will probably lead to us coming to a standstill on the deeper issues of our disagreement that can't forseeably be resolved.