This may sound weird, but looking back over the years it makes a certain kind of sense: I think you need to be exposed to kittens/puppies/unexpected-births as a youngster, in order to acquire a responsible attitude towards breeding in general (even within your own species*) as a adult.

Yes we had the proverbial one-litter-too-many when I was a teenager. Yes I was intrigued by the possibility of my friend's pedigree hound being 'accidentally-unofficially' bred with another hound, on the understanding that the bitch and litter would be mine... no I did not go through with it.

*: yes I am still being incredibly picky, to the point I haven't mated yet ;)