It's better to admit you can't handle it than to make a mess of some small human's life.
There's "can't handle it" and then there's "don't want to". I know I say this often (probably too often), but not wanting kids is more than enough reason. No need to dwell too long on whether or not one can handle it if one doesn't feel a strong, sustained urge (not a "pang" or even a series of "pangs").
Every once in awhile I'll have a transient "baby pang" around a friend's kid. But I also have transient "horse pangs" around my horsey pals, and "Porche pangs" around my wealthier friends with nice cars, which are at least as strong! The point is that I'm well aware of what I would have to do to have a horse or a Porsche (give up a huge amount of my free time in the former case --- I've worked as a horse groom in the past and I know what it takes --- or, in the latter case, get a higher-stress, higher-paying, non-music job so I could afford those sports car payments. Those are not trade-offs I wish to make.
The problem is that most folks don't acknowledge that there even *are* tradeoffs to having kids, even though they're there for everything else. Society only wants us to see the upside. I've always said that if the product was so wonderful, it wouldn't need such unerrantly thorough PR.
Another cool bumper sticker: "It's no longer fruitful to multiply" (not really a CF sentiment per se, but rather a suggestion of zero population growth).
Elise