Data: Which explains American social mobility better? Sociology or biology?

I remember the first department party I attended as a PhD student in sociology.  I joined a conversation between a young faculty member who specialized in social mobility and a professor who was an international expert on urban sociology. I was stunned when the older guy said to the young guy, "Why do you study American social mobility? There is no such thing."

I had a bigger mouth then, and said, "Could've fooled me. My parents never stepped foot on a college campus. I have one brother working on his JD and another has a BS in business and will probably make double what I end up making." (Turned out to be more like three times as much.) He said something about exceptions and moved on to something else.

So the sociological view is that kids inherit the social class of their fathers because the system is rigged that way. The logic of this theory is that there should really be few exceptions. The genetic view, on the other hand, is that since children get their genes from parents, they will tend to end up where their parents are, but since each child gets a unique combination of genes, and since each child is exposed to unique developmental events, offspring will often depart from the class of their parents by either moving up or moving down. The pure sociological view has no explanation for these departures. An open, fluid, meritocratic America is a fiction, according to these people.

What does the General Social Survey say?  You can see below a contingency table of father's and offspring's highest degree earned (sample size = 1,325, ages 30-39, years 2010-16). (I use education because we have data for both generations):

 

As both theories predict, there is a tendency to end up where the old man did, but there are PLENTY of exceptions. 

Adding up all the cells where the kids went further in school than dad, we get 35% of the total. If we do the same for all offspring that fell short of their father's education, we get 15% of all respondents. Yet we're told you're never supposed to be able to fall in American society where privilege reigns. 

Intergenerational stasis happens to just 50%. This pattern is consistent with a genetic/developmental theory of outcomes. It does not support the opinion of my America-hating professor.

What causes a person to climb the ladder of success?

Here's the abstract from a new genome-wide association study on social mobility. Sounds about right to me: 

A summary genetic measure, called a “polygenic score,” derived from a genome-wide association study (GWAS) of education can modestly predict a person’s educational and economic success. This prediction could signal a biological mechanism: Education-linked genetics could encode characteristics that help people get ahead in life. Alternatively, prediction could reflect social history: People from well-off families might stay well-off for social reasons, and these families might also look alike genetically. 

A key test to distinguish biological mechanism from social history is if people with higher education polygenic scores tend to climb the social ladder beyond their parents’ position. Upward mobility would indicate education-linked genetics encodes characteristics that foster success.  

We tested if education-linked polygenic scores predicted social mobility in >20,000 individuals in five longitudinal studies in the United States, Britain, and New Zealand. Participants with higher polygenic scores achieved more education and career success and accumulated more wealth. However, they also tended to come from better-off families.  

In the key test, participants with higher polygenic scores tended to be upwardly mobile compared with their parents. Moreover, in sibling-difference analysis, the sibling with the higher polygenic score was more upwardly mobile.  

Thus, education GWAS discoveries are not mere correlates of privilege; they influence social mobility within a life. Additional analyses revealed that a mother’s polygenic score predicted her child’s attainment over and above the child’s own polygenic score, suggesting parents’ genetics can also affect their children’s attainment through environmental pathways. Education GWAS discoveries affect socioeconomic attainment through influence on individuals’ family-of-origin environments and their social mobility.

More on class and marriage: A reader outlined some limitations to using occupational prestige as a measure of class. In addition to his points, I was dissatisfied with the gender factor in general: a wife could easily come from a high status family, but might not pursue a prestigious career. Looking at education gets around some of these problems, so here are correlations among the same groups I listed in the earlier post:


Pearson correlation coefficients

Father's educ.--Respondent's educ., .49
Respondent's educ.--Spouse's educ., .62
Father's educ.--Spouse's educ., .44

Now these correlations are definitely stronger than when occupational prestige is used. How far you it make it in school depends a lot on Dad, but getting a successful career is more out of his hands.

It seems to me that the most important reality in all this talk of marriage is the simple principle of "homogamy." At least in the American context, it's not so much that you marry someone whose family is like yours in terms of status--you marry someone very much like yourself. Family is correlated with those characteristics, but modestly. This focus on family status is, I think, more on the minds of elites than ordinary people.

Now Steve's definition seems to focus on parental concern, but in American society, anyway, "concern" looks less like influence and more like hope. I know my working-class parents never cared in the least that I associate with people of a certain status: they only wanted me to hang out with good people. My parents would have been perfectly happy if I married a girl with only a high school degree. As for my sister's spouse, they only cared about character, not status. It makes sense that the higher your position, the more that class is a real issue since the people at the top can only maintain or move down.

Does social class determine marriage? Steve Sailer has put forward the idea that "class is about who your descendants are likely to marry." But just how meaningful is any definition of class is contemporary American society? Below, I present Pearson correlations between your father's occupational prestige when you were 16, yours now, and your spouse's. (It would be nice to look at your spouse's father's occupational prestige, but the GSS doesn't have it):


Pearson correlation coefficients

Father-respondent .31
Spouse-respondent .39
Father-spouse .27

These connections are pretty weak. The one that most directly measures your family's class with that of your spouse's is the last one listed, and it is only .27. If this correlation were not reduced by the influence of controls in a multivariate analysis, then your family's class explains about 10% of your spouse's class.

It is possible that a direct measure of your spouse's father's class might be more highly correlated with your own father's, but it seems doubtful when these numbers show that there isn't much of a correlation between your father's class and your own as an adult. The fluidity and individualism of American society makes the idea of class less meaningful.

Bias against the rich takes another knock: We all know that if your born into a rich family, your future is guaranteed, right? Some Americans go from rags to riches, but Daddy will make sure the opposite never happens. The General Social Survey asked respondents about their occupations and those of their fathers. I looked at the 262 men whose fathers had prestige scores in the top 10%. If the "silver spoon" hypothesis is correct, all these guys should have prestige scores at least as high as Pop's. On the other hand, if the process were purely random, only 10% of the sons would equal Dad's accomplishments. So what do the data tell us? Only 26.4% of these guys equalled or surpassed their childhood status. Basically three-quarters of them were riches to rags (well, not rags usually, but you get the picture).

Of course, a person is not surprised by this if he is familiar with the idea of the regression to the mean, but in our innumerate society, few are. (By the way, "he" was used intentionally in the last sentence).

(And don't think that I'm some richie trying to defend my class: I'm the son of a maintenance man.)