I think I was about 14 when I realized I'd never WANT children. Other girls would coo over babies in prams, and I'd just think "yuk, all that poo and dribble!" I seem to have had a maternal bypass, which isn't surprising as I don't think any of the women in my family, bar one, ever actually craved, or really wanted, children. So I guess there's a bit of unconscious conditioning there. I'm told I'm 'marvellous with children', but anyone can be that when you just treat them cordially, and then go home without any responsibility for them! But I think it's a bit unreasonable to be 'desperate to have kids' when the man you've set your cap at has had a vasectomy! That means 'kids of your own' and not just kids per se, doesn't it? You could always foster needy children, or adopt the orphaned or abandoned, but it doesn't seem to be 'enough' for some.
I don't dislike the little buggers, but I never wanted the preggers/baby/toddler bit. I prefer the idea of the 'Instant Ten Year Old - just add water, and a delightful 10-y.o. child is yours, ready to play! Choose the blue packet for a boy, the pink packet for a girl, or the lilac for a Julian Clary Special!"