A few years ago, I ended up on the wrong side of this response:
"Wait, I love my kids! STOP TALKING ABOUT KILLING MY KIDS!"
I found this a little confusing, as we weren't talking about killing anyone. However, I've since become a parent, and I can offer an explanation and translation.
When you become a parent, there's an overwhelming joy at having created an entirely new and perfect person (perfect until you and the world get at them). On the other hand, there are more than a million things that you personally can screw up on and three times that which are completely outside of your control. From the very beginning, it can lead to nightmares where you get a surprise phone call from a friend:
"Go to YouTube and search for your kid's name."
Accordingly, parents get together to share notes and say things that will make each other feel better. A distributed, random, high-population support group, as it were. I am a fervent participant in this system.
However, some parents need more than that shared comfort.
Now, let's put another character trait into the mix: some people aren't just right, they're awesomely right, and they have to share that joy with you... even if tends to come across in passive aggressive ways.
"I love being married! Everyone should get married! Dating was so horrible. Honestly, I look back on the days of being single and shake my head because my life was chaotic and lonely back before I got married."
This kind of statement doesn't have anything to do with the subject — being married, being a parent, or whatever else — but with any big investment you want to feel like you did the right thing.
"Last week, I entered into a new business where I have unlimited opportunity. I can say that it's easily the best job I've ever had, and more than that, it's the best job I've ever heard of. And you can be a part of it, too! Have you ever heard of Amway?"
There is no bigger investment than having children. Since waiting to see if this is the right decision is slow and, you know, of uncertain outcome, it's easier to find validation in proclaiming to anyone who will listen how everyone could be made happier by following your lead.
"I'm a writer! Look, I've sent out short stories for consideration by the editors of small-press publications! I'm pursuing artistic endeavors as a vocation! I am a writerrrrrrrr!"
So when parents are joyful and enthusiastic about their own kids and mix that up with the thought that a person can't unchild themselves without being a really bad person, a kind of mania can attach to the love. Like everything else in life, certain people are going to handle this gracefully, some with humor, and the rest of us with a couple of olives resting at the bottom of the glass.
I can say from firsthand experience that I've never been as happy, sad, or angry as I've been during the time that I've had children. The emotional level is powerful, so it can turn normally balanced-enough people into the kind of person who could say:
"I love being a parent! Kids are the best!"
...into the kind of person who would say:
"I don't mean any offense, but anyone who doesn't have kids must be barren and empty on the inside."
Now, this isn't a problem for most people. You can sense when someone's a little crazy. But some people, including the younger version of myself, end up thinking of such a statement rationally. Then, mistaking that they are talking to an otherwise rational adult, will offer the counter viewpoint:
"Can't a person be happy without kids? Could you be happy without kids?"
New parent thinks, "Well, gosh I haven't thought about it in so long... what would have to happen for me to be childless. Oh right, my kids wouldn't exist!"
And then: "STOP TALKING ABOUT KILLING MY KIDS!"
I'm a very happy father of two, but I very clearly remember the other side. Hanging out with kids isn't for everyone, and becoming the parents of kids isn't for everyone.
Childless cool people, please forgive us uncool parents. Becoming a new parent is emotionally charging. We don't mean any harm.