Modern Farmer has an article on "boar taint*" for which they interviewed Walt Jeffries of Sugar Mountain Farm. Walt has bred "boar taint"out of his herd. The issue raised in the article is whether it's okay to use genetic modification methods to remove the cause of boar taint from the genome of pigs. Unlike the usual objections to GMO's, which involve transferring DNA from another species into a genome, this is an edit, an edit which as Walt has shown can be done using conventional breeding techniques. (I raised a similar question in connection with wheat in this post.)
I suspect as we improve our understanding of genetics similar questions will come up.
* it's something which makes pork from boars unmarketable--see the link if you really want to know.