My father and my mother met at a venerable English university. I went to the same place, as did two of my sisters. Now that my stepbrother has followed in our footsteps, I am starting to think that there may be more than coincidence behind the whole business.

    if we accept that fluke is an unlikely explanation for the uniformity of the Harford educational experience, it is an example of what economists call “intergenerational transmission of educational attainment”. Intergenerational transmission of income is a closely related issue: do the children of rich parents grow up to be rich, and do the children of poor parents grow up to be poor?

    The simple answer is that it depends in which country they live. In the US and the UK, if your parents were twice as rich as the average for their generation, you could expect to be 40 per cent richer than the average for your generation and so your children could expect to be about 16 per cent richer than the average for theirs.

    Sensible readers will be wondering whether that suggests a lot of intergenerational income mobility or not. I do not know the answer: it's very hard to say what we should expect, or want. What we do know – thanks to the efforts of Gary Solon, a professor at the University of Michigan and a leading light in the field – is that the transmission of income down the generations is higher than we used to think. Estimates from the 1970s and 1980s, which suggested much lower income persistence, were dogged by poor data.

    We also know that rich parents are much more likely to have rich children in the US, UK and France than Canada, Sweden or Denmark. In Denmark, if you are twice as rich as the average, your children will tend to be just 15 per cent richer than the average. (These international comparisons come from a survey by Miles Corak of Ottawa University.)

    Solon thinks these findings are “just the beginning of a discussion, not the end”. He has a good point. Should policy try to respond to the fact that I went to the same university as my parents? That rather depends on whether I got in because my father called in a favour from the tutor for admissions. What if I simply benefited from a family love of books, or even inherited some bookish genes? It is hard to imagine any but the most totalitarian state doing much about that.

    While we think of intergenerational income mobility as a sign of meritocracy, if we did live in a genuine meritocracy, it is hard to know how much mobility we should expect to see. People have a certain kind of “merit” in mind when they speak glowingly of a meritocracy, and that kind of merit tends to run in the family.

    That is true for both genetic and cultural reasons. A fascinating new study, co-authored by Solon, looks at a remarkable set of data on adopted Swedish children. The researchers have data on all four “parents” – two biological and two adoptive – and use it to look at the correlation between the parents' level of education and the child's. It turns out that all four parents influence the child's educational level. (If anything, sharing genes has a stronger influence than sharing a home; there is not much in it.)

    If, as Solon suggests, this is just the beginning of a discussion, where should the conversation go now? Many economists believe that we should be looking for effective interventions to improve the health, nutrition and education of pre-school children in an attempt to level the playing field. It is not yet clear whether we shall find them.  

    我的父親和母親在一所歷史悠久的名牌大學(xué)中相遇。我和兩個(gè)妹妹上的也是同一所大學(xué)。由于我同父異母的弟弟現(xiàn)在也追隨了我們的足跡，我開始認(rèn)為，整個(gè)事情可能不僅僅是巧合。

    如果我們承認(rèn)，不太可能用“偶然”來解釋哈福德家族教育經(jīng)歷的一致性，那么這就是一個(gè)經(jīng)濟(jì)學(xué)家稱之為“兩代人之間教育成就的傳遞”的例子。兩代人之間收入的傳遞是一個(gè)密切相關(guān)的話題：父母富有，他們的孩子長大了就會(huì)富有嗎？貧窮父母的孩子長大了也會(huì)貧窮嗎？

    簡單的答案是，這取決于他們生活在哪個(gè)國家。在美國和英國，如果你父母的富裕程度是他們那一代人平均水平的兩倍，那么你的富裕程度就可能比你這一代人的平均水平高40%，而你子女的富裕程度就可能比他們那一代人的平均水平高16%左右。

    敏感的讀者會(huì)想知道，這是否意味著兩代人收入之間存在著高度的流動(dòng)性。我不知道答案：很難說我們應(yīng)該期望或者希望看到這種流動(dòng)性。我們知道的是——這要感謝密歇根大學(xué)(University of Michigan)教授、該領(lǐng)域重要人物加里•索倫(Gary Solon)的努力——收入在世代之間的傳遞程度要比我們過去認(rèn)為的要高。上世紀(jì)70年代和80年代的估計(jì)顯示，世代之間的收入連續(xù)性要低得多，這是受到了數(shù)據(jù)質(zhì)量不佳的影響。

    我們還知道，在美國、英國和法國，父母富有、子女也富有的可能性要比加拿大、瑞典或丹麥高。在丹麥，如果你的富裕程度是平均水平的兩倍，那么你孩子的富裕程度往往僅會(huì)比平均水平高15%。這些比較來自渥太華大學(xué)(Ottawa University)邁爾斯•克拉克(Miles Corak)進(jìn)行的一項(xiàng)調(diào)查。

    索倫認(rèn)為， 這些發(fā)現(xiàn)“僅僅是一場討論的開始，而非結(jié)束。”他說的很對(duì)。政策是否應(yīng)當(dāng)對(duì)我和我的父母上同一所大學(xué)這一事實(shí)做出回應(yīng)？這可能取決于我之所以能入學(xué)，是否因?yàn)槲腋赣H請(qǐng)導(dǎo)師幫了忙。如果我僅僅是因?yàn)槌錾�在一個(gè)熱愛讀書的家庭而獲益，或者甚至是繼承了一些好學(xué)的基因，情況又如何呢？很難想象即便是最集權(quán)主義的國家能在這方面采取什么措施。

    盡管我們認(rèn)為兩代人之間的收入流動(dòng)性是一種精英體制的標(biāo)志，但如果我們的確生活在一個(gè)真正的精英體制中，很難知道我們應(yīng)當(dāng)希望看到多大程度的流動(dòng)性。當(dāng)人們稱贊一個(gè)精英體制時(shí)，他們腦海中存在著某種“優(yōu)點(diǎn)”，而那種“優(yōu)點(diǎn)”往往在家族中流傳。

    這從基因和文化角度而言都是正確的。索倫與他人合著的一份有趣的新研究報(bào)告，探討了一組關(guān)于瑞典領(lǐng)養(yǎng)兒童的數(shù)據(jù)。研究人員擁有關(guān)于四位“父母”——兩位生身父母和兩位領(lǐng)養(yǎng)父母——的數(shù)據(jù)，并用它來研究父母教育程度與子女教育程度之間的關(guān)聯(lián)。結(jié)果表明，所有四位父母都會(huì)對(duì)孩子的教育程度產(chǎn)生影響。（如果說有什么區(qū)別的話，擁有相同的基因比擁有同一個(gè)家具有更大的影響，但差別不大。）

    正如索倫指出的那樣，如果這僅僅是一場討論的開始，那么這場對(duì)話將向何處發(fā)展呢？許多經(jīng)濟(jì)學(xué)家認(rèn)為，我們應(yīng)當(dāng)尋求進(jìn)行有效的干預(yù)，以改善學(xué)前兒童的健康、營養(yǎng)和教育，以此創(chuàng)造公平的競爭環(huán)境。目前尚不清楚我們能否找到這些措施。