Thank you for your thoughtful response Frederick. I would never posit this point in relation to a real, live breathing person!

For me, it's not what my child could potentially do for the world, but rather that my desire as a parent is they should have access to unpolluted air, water etc, and those children already alive deserve to be cared for, rather than the (to me) egotistical compulsion to have my 'own' children.

It's a very personal decision, partly also shaped by me having been given too much responsibility as a child, for my younger siblings.