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.  

    我的父亲和母亲在一所历史悠久的名牌大学中相遇。我和两个妹妹上的也是同一所大学。由于我同父异母的弟弟现在也追随了我们的足迹，我开始认为，整个事情可能不仅仅是巧合。

    如果我们承认，不太可能用“偶然”来解释哈福德家族教育经历的一致性，那么这就是一个经济学家称之为“两代人之间教育成就的传递”的例子。两代人之间收入的传递是一个密切相关的话题：父母富有，他们的孩子长大了就会富有吗？贫穷父母的孩子长大了也会贫穷吗？

    简单的答案是，这取决于他们生活在哪个国家。在美国和英国，如果你父母的富裕程度是他们那一代人平均水平的两倍，那么你的富裕程度就可能比你这一代人的平均水平高40%，而你子女的富裕程度就可能比他们那一代人的平均水平高16%左右。

    敏感的读者会想知道，这是否意味着两代人收入之间存在着高度的流动性。我不知道答案：很难说我们应该期望或者希望看到这种流动性。我们知道的是——这要感谢密歇根大学(University of Michigan)教授、该领域重要人物加里•索伦(Gary Solon)的努力——收入在世代之间的传递程度要比我们过去认为的要高。上世纪70年代和80年代的估计显示，世代之间的收入连续性要低得多，这是受到了数据质量不佳的影响。

    我们还知道，在美国、英国和法国，父母富有、子女也富有的可能性要比加拿大、瑞典或丹麦高。在丹麦，如果你的富裕程度是平均水平的两倍，那么你孩子的富裕程度往往仅会比平均水平高15%。这些比较来自渥太华大学(Ottawa University)迈尔斯•克拉克(Miles Corak)进行的一项调查。

    索伦认为， 这些发现“仅仅是一场讨论的开始，而非结束。”他说的很对。政策是否应当对我和我的父母上同一所大学这一事实做出回应？这可能取决于我之所以能入学，是否因为我父亲请导师帮了忙。如果我仅仅是因为出生在一个热爱读书的家庭而获益，或者甚至是继承了一些好学的基因，情况又如何呢？很难想象即便是最集权主义的国家能在这方面采取什么措施。

    尽管我们认为两代人之间的收入流动性是一种精英体制的标志，但如果我们的确生活在一个真正的精英体制中，很难知道我们应当希望看到多大程度的流动性。当人们称赞一个精英体制时，他们脑海中存在着某种“优点”，而那种“优点”往往在家族中流传。

    这从基因和文化角度而言都是正确的。索伦与他人合著的一份有趣的新研究报告，探讨了一组关于瑞典领养儿童的数据。研究人员拥有关于四位“父母”——两位生身父母和两位领养父母——的数据，并用它来研究父母教育程度与子女教育程度之间的关联。结果表明，所有四位父母都会对孩子的教育程度产生影响。（如果说有什么区别的话，拥有相同的基因比拥有同一个家具有更大的影响，但差别不大。）

    正如索伦指出的那样，如果这仅仅是一场讨论的开始，那么这场对话将向何处发展呢？许多经济学家认为，我们应当寻求进行有效的干预，以改善学前儿童的健康、营养和教育，以此创造公平的竞争环境。目前尚不清楚我们能否找到这些措施。