Person: I do not want children. I feel guilty about this as it is my responsibility to have them.
Z: Studies show that every U.S. child born is highly detrimental to the environment no matter how green their lifestyle. There is no reason to feel guilty about not having them.
Person brightens.
Bystander (to Person): How can you look happy when you were just told something so mean?
Axé.
coldhearted scientist وداد 
Bystander has issues. Capital-I issues. And is rude, besides.
What is interesting is that in this culture, the view I voiced was “rude” — views and attitudes that are not conformist are rude!
You made Person feel better, so why should Bystander care? And Person shouldn’t need validation about that. You have children or you don’t; no one has the right to weigh in either way, and it’s bad manners to make someone feel bad for that choice.
Fair numbers of people who have kids would be far happier without them. I think it’s great when people who don’t want kids don’t have them. Whether saving resources is what it’s about I rather doubt, since I don’t see anyone I know, with or without children, seriously cutting back on much of anything in order to save the planet.
Adding to what Hattie says: people do what they want to do, justify their choices to themselves, and lecture others about choices that they’ve deemed to be lesser. It’s an unpleasant but common part of human nature. Back in the day, I had a friend who lectured my family about healthy food choices because there was some fake creamer in the house, like Coffee-Mate. She sat there and smoked as she lectured us. Lesson learned: listen to no one about your choices unless you want to do so.
And, as you’ve probably gathered, that means I don’t listen to people about my choices any more unless they have actual information to impart–which is rare.
Yes but in our culture I was effectively lecturing Bystander and putting down her choices. I have had it confirmed that it is in fact deepy offensive to say anything pro-environment or not adamantly pro-procreation within earshot of anyone who might be hurt by these ideas–or more accurately, to put environment ahead of procreation, as I did.