I see children as being like bamboo -- you'd better be damned sure you want 'em before you plant 'em
and also about Doctor/Companion relationships:
Doctor and Rose sitting in a tree
First comes love,
then comes [censored],
then comes nothing at all because the Gallifreyans have had several thousand years to think out the whole contraception thing, thanks so VERY much, and anyway Rose is nineteen and knows far too many unmarried mothers.
- in comments here. QWP.