I heartily despise any and all children that haven't learned to walk, talk, and speak clearly enough to tell me what's wrong. I can't fix the problem if I don't know what it is, and nine times out of ten (for me, at least), the issue gets worse before I can figure out what's wrong. Not only that, but they're loud, rude, messy, and require an obscene amount of upkeep for years before they can actively handle even basic things on their own.
The method by which they mature before birth bothers me as well. They're latched onto the inner workings of the mother, or 'host' in my interpretation, and are continually siphoning off vital nutrients from the parent, wreaking havoc with her hormones and appetite, and generally sabotaging her bodily structure in painful and disturbing ways. I view it as a parasitic infection that a "miracle of life" that some people claim it to be.
Don't even get me started on the actual birthing process. XS
All of this, however, is just my opinion on it. I just REALLY don't like young children. Dr. Suchong said it best, I think, when he was pondering the growth of children. Cookies if you know what he said.
EDIT: I don't need the 'emotional gains' that children can bring, either. I have a dog for the outdoorsy super fun playtime stuff, and a rabbit for the soft cuddly, lovey-dovey bits. They're cute, fuzzy, and very quiet as well, so that's three up on the wrinkly little merde-makers.