When he was Prime Minister, Tony Blair had a lot to say about ‘equality of opportunity’ – which was his way of moving on from the Old Labour attachment to ‘equality of outcome’. Commenting on Blair, a Conservative MP once told me that Conservatives shouldn’t believe in either form of equality.

Knowing this MP to be a thoughtful and compassionate man, I was, at first, somewhat surprised. How could a modern Conservative not believe in opportunity for everyone? How can you have an ‘enterprise society’ without it?

His reasoning, however, was perfectly sound – the relevant question, he said, is this: How are you going to equalise opportunity? Many of our most important opportunities are given to us by our parents in childhood – through simple acts like reading to us at bedtime – so how can we possibly equalise that?

Liberal egalitarians tend to think of opportunity in purely material terms – and thus focus on factors such as household income and state spending on education. However, the evidence that the home environment has a huge impact on educational and economic outcomes has become impossible to ignore.

The issue is addressed in a new book, Family Values: The Ethics of Parent-Child Relationships, by the academics Harry Brighouse and Adam Swift – described by Jonathan Derbyshire as “a liberal egalitarian case for family values.”

Derbyshire interviews Swift for Prospect:

“…the more that sociologists investigate the detailed processes the more it looks as though the reason more advantaged parents tend to have kids who lead more advantaged lives is because of the stuff that goes on informally within the family—the transmission of cultural capital, taking your kids on holiday, having books in the house, reading bedtime stories and so on. And so the sense in which this is bad news for progressives is that we can’t respect family life without taking a hit for fair equality of opportunity.”

Where these principles come into conflict, Brighouse and Swift come down on the side of respecting family life:

“…if we had to choose between a world where you had fair equality of opportunity, but at the cost of loving familial relationships, that would be worse than a world in which we have loving familial relationships but in which we can’t provide people with fair equality of opportunity.”

Of course, it shouldn’t take thousands of words of academic hemming-and-hawing to reach this conclusion. Moreover, there’s something quite chilling about holding the family subject to egalitarian social objectives:

“What kind of parent-child interaction do we need to respect even though they will produce unfairness? And what kind of parent-child interaction do we, on reflection, not need to respect because, although we currently allow parents and children to engage in them, they’re not actually required for healthy familial relationships?”

To most of us on the centre-right, the answer to these questions is ‘mind your own business’ (or words to that effect). And yet it would be a mistake to view that whole question of family values as a purely private one. Public policy can make a difference precisely by respecting – and actively promoting – the family structures that give children the best start in life.

In other words, the compassionate conservative response to inequality in this matter (as in most other matters) is neither laissez faire nor to level down, but to level up.

However, that would mean politicians showing some leadership on issues like marriage – and braving a backlash that won’t just be confined to the liberal left.