In the long term it means that you don't pass your set of values onto the latter generations.
> consciousness about the environment does not transmit through genes
Intelligence, conscientiousness and empathy are all heritable to a degree. More importantly, your kids will likely inherit most of the socioeconomic factors that made you become environmentally-conscious in the first place. And I'm assuming you want the next generations to be as eco-friendly as possible.
I'm also incredibly skeptical of the environmental impact of antinatalism among hardcore environmentalist first-worlders vs the exploding birth rates across the globe. It just seems performative and hairshirty.
Education, activism, involvement in the community, publishing research, etc. are all effective ways to pass on values to future generations. Nudging the overton window of society is arguably a much more effective way to pass on values.
> Intelligence, conscientiousness and empathy are all heritable to a degree.
Nowhere near enough to keep up with technological and societal change.
> More importantly, your kids will likely inherit most of the socioeconomic factors that made you become environmentally-conscious in the first place. And I'm assuming you want the next generations to be as eco-friendly as possible.
Those kids would need to have a net-positive contribution to the environment for this argument to make any sense. It also seems mostly irrelevant to the argument about whether to have kids or not: any virtue you ascribe to those potential kids can also be ascribed to anyone else: if those kids could be a net-positive to the environment, why not the friends and neighbours that are already here? If influencing others in similar socioeconomic situations is beneficial, we can find plenty of those people around already. And so on.
> exploding birth rates across the globe
Do you have a source for this? All the evidence I've seen says the exact opposite (e.g. the UN's data and projections for this century show birth rates declining across every continent https://population.un.org/wpp/DataQuery )
Edit: I have 2 children (we went through 8 rounds of IVF for those 2 buggers), would probably have more if we could but funds are tight now. Though, we might adopt. Luckily insurance paid most of it back when I wasn't freelancing. So, I say this even though I don't have a huge family of 6+ kids, but if you're up to the challenge I salute you!
Adoption is also admirable and while you're not passing genes, you can pass on values and your ethical systems to a new generation so if you want to help the environment by not having kids but also change things generationally --think about fostering and adoption. We used to be foster parents and it'll change your entire viewpoint on life, it's hard though when the kids are reunified with the family even though mom and dad are still doing drugs... lots of heartbreak there, but it's worth it for the difference it makes.