Every child that's born is a child that will eventually need their own shelter. Will probably drive their own car. Will need food.
The best way to reduce your carbon footprint is to not have children.
All I'm saying is that our current population growth is unsustainable and we're killing the environment. Until we adapt to only consume renewable resources, or at least sufficiently reduce our consumption of non-renewables, and stop pumping CO2 into the atmosphere, the best thing to do is slow down reproduction.