Earlier quoted context omitted.
My inner pessimist is expecting to see a "there was this Daily Mail article one time". Everywhere I look, I see the opposite. Families with a comfortable amount of disposable income have the 2.4 kids, but those in poverty (and particularly the working poor) have 3, or upwards. Anecdotal, but I'm yet to see evidence to the contrary
There's evidence on a national scale that birthrate is anticorrelated with wealth. The better off people are on average, the less kids they have.
If you try and slice it by family you find that the 'traditional' family makes up a fairly small percentage of the population.