Originally Posted by
fairymuff
Basic probability theory says he/she won't.
Seriously: the cumulative effects of children and their potential offspring outstrip any other thing you could do for the environment.
You don't know that they're going to have offspring of their own for one thing. Odds are that if you have only two kids, your progeny will eventually die out.
Personally I work in the field of energy conservation and I have been for the last 15 years so I've had a hand in saving quite a bit of energy, much of which has been in large commercial lighting projects. As of a couple years ago I had already saved the amount my 2 kids would likely use in their lifetime.