This week, the Deputy Prime Minister unveiled indicators the government will be using to measure the extent of social mobility in the UK – in other words, the degree to which labour market success is determined by the socio-economic status of your parents.

In today’s economy, now more than ever, high human capital is critical for future individual prosperity and health. So educational attainment is critical for social mobility. Just look at the premium from attending university: on average, £108,000 over a lifetime. [2]

Parental background, particularly in countries such as the United Kingdom with high income inequality, is a key determinant of social and economic outcomes.  But, despair not, because our genes and our parents don’t have to determine our destiny: high-quality educational institutions - schools and especially nurseries - can mitigate the disadvantages associated with growing up poor.

Good schools have good teachers. A wealth of US literature shows that children who have effective teachers reap significant long-term rewards: in one study [3], pupils learning from an excellent teacher for just one year gained on average a quarter of a million dollars more in their lifetime earnings than similar students who didn’t.  For the British Government, fretting about the country’s decline in the international league tables for students’ reading, the key task is to drive up the quality of teaching.

We have financial incentives for high-quality graduates to join the profession, with discounts on the repayment of their tuition fee loans. And the House of Commons Education Select Committee has recently proposed performance-related pay for teachers. But the Secretary of State’s main mission is supply-side liberalisation to encourage more choice - through more free schools – and to increase competition – through greater autonomy for schools from local authorities and Whitehall to allow freedom to innovate.

Promoting choice and competition is the right direction of travel, but there are limits to how effective the current strategy will be. Many parents and community groups simply do not have the capital, especially when government won’t fork out, to set up new schools to facilitate greater choice. And government, wrongly, will not allow for-profit providers to set up schools. As Nick Clegg’s special adviser commented [4] in the FT last year, “If nothing changes a few good schools will open, but not the hundreds needed for competition to have an impact on standards”.

In fact, a half-baked choice strategy can have damaging implications for the most disadvantaged pupils. When choice is limited, there is no competitive pressure on poor performing schools, which can fill their rolls regardless. Meanwhile parents with more resources monopolise the best schools, effectively buying a place by having the funds to move into the catchment area. This dynamic is confirmed by research [5] from the Centre for the Economics of Education at the LSE, which showed that the modest expansion of choice for parents in some parts of England led to children from the same socio-economic background being more likely to be educated together.

Increased segregation then compounds the social mobility problem. Work by OECD [6] in 2009 demonstrated that there is a significant advantage for poorer students to be educated in socially mixed schools, and this has no negative effect on overall performance. Without mixed school populations, the attainment gap between rich and poor children just widens.

So, how can we use parental choice without it resulting in damaging social segregation? A school-specific lottery for admissions would help. Here, parents could be free to apply to a school of their choice. Where schools are over-subscribed, places would be allocated in full or in part by a lottery, rather than by catchment areas, giving a greater chance to ambitious poorer parents who didn’t have the funds to move into the local area. Why not insist that schools do this if they want pupil premium funding or academy status?

Another mechanism would be to incentivise more affluent parents to hedge their bets on sending their children to a school which traditionally doesn’t do as well in the league tables. In the late 1990s, Texas introduced a rule where pupils who were in the top 10% for exam results in every school were automatically guaranteed a place at a state university. Recent research [7] has shown that the policy led to greater social diversity in schools.  It would be possible to apply this scheme in the UK without undermining the independence of universities, by creating a pool of extra places universities could bid for which includes the top 10% of students from a select number of schools.

Parental choice is an important tool for driving up quality in schools. But we need to be realistic about its limits when public money is short. The challenge is to use choice to improve performance while avoiding the unintended consequences of entrenching disadvantage through social polarisation. Lotteries and an adaption of the Texas 10% plan are ways to square this circle.

Ryan Shorthouse is a researcher at the Social Market Foundation [8]