Fatherhood and the Law of Regression

Maybe every generation thinks the next one is the end of it all. I bet there are people in the bible walking around complaining about kids today. – Roger Sterling, Mad Men, Season 1, Episode 4

I recently explained why oddballs and misfits can rise to prominence without their characteristics necessarily offering any adaptive advantage (Krueger, 2025). I referred to two Darwinian tenets, one being nature’s overproduction of offspring, and the other being the observation that the survival of the fittest ensures that species are just about as well adapted to their environment as they can be.

Add to this the Darwinian tenet that mutations are random, and we see that most mutations are either neutral or harmful with regard to fitness. Harmful mutations, by definition, reduce the likelihood of reproduction, but each subsequent generation will see a new crop of less-than-perfectly adapted organisms. New negative mutations will emerge at random.

The validity of these tenets and their implications is, I believe, inarguable. Heads nod when we talk about organisms in an abstract or general way, but egocentric and moralistic sentiments emerge once we talk about human beings or—Darwin forbid—ourselves. So, I have to beg your patience as we explore this line of thought further.

The Law of Regression

The argument I wish to make is that, because of the Darwinian tenets stated above, we may say that sons are, on average, less distinguished than fathers, and that in spite of this, we need not worry about a slow slide into idiocy. The cause of this father-son differential is, in brief, that every son has a father, whereas not every son will be a father. The argument holds to a lesser degree for mothers and daughters.

Coming from a distinguished family himself, Sir Francis Galton, a half-cousin of Charles Darwin, observed that the most eminent men had less eminent sons, although most of those sons were still above average. He published a book, the famous Hereditary Genius (Galton, 1869) to explain this curious phenomenon to himself, and in the process discovered the law of statistical correlation and regression. He indicated correlation with the letter r, which stands for regression.

As genius is difficult to measure, the textbook demonstration, introduced by Galton himself, uses men’s physical height. Suppose the average height is stable over generations. Thanks to heredity, the height of sons resembles the height of fathers, and, statistically, we see a robust positive correlation. Also, assuming that the standard deviation of height is the same for fathers and sons, we notice that very tall fathers have somewhat shorter sons. The other side of the statistical coin is that very short fathers have sons who are not quite as short as they, the fathers, are. Statistics doesn’t care who goes first. The tallest sons have shorter fathers, and the shortest sons have taller fathers (Fiedler & Krueger, 2012).

The Inequality of Reproductive Success

Galton and latter-day statisticians focus on father-son pairs so that they can compute correlations. Populations in the wild, however, comprise some fathers who have many sons and many sons who will not be fathers. This follows from the Darwinian tenets above. Nature overproduces individual offspring, but not every offspring will reproduce. The ability to reproduce is the currency of success in this biological world.

I realize that we have to accept a leap of inference and judgment when we say that successful paternity is a biological signal of “goodness.” I will let this stand for the moment and leave it to philosophers and moralists to debate the finer implications and meanings.

What does this biological foundation imply for the psychology of fathers and sons? Fathers and sons know that the fathers have already succeeded in one important way, by becoming fathers and doing the hard work of raising sons. This realization puts pressure on the sons. Will they be able to achieve the same?

Fathers loom large in sons’ psychological world, often in both a positive and a negative way. Good fathers should be emulated, and lesser fathers can still serve as negative role models. They teach their sons what not to do.

Many sons, consciously or otherwise, will ask themselves whether they will be able to achieve what their fathers achieved, and some will fail (I am not disputing the reality that some sons will never wish to become fathers, and I am not insinuating any value judgment).

Evolutionary Psychology Essential Reads

Sex Before Sexes: The Evolutionary Case for the Female First

What’s in a Color? For Humans, a Great Deal

Why is the biostatistical logic described here more poignant for men than for women? Darwin (1871) offered an answer in his theory of sexual selection: Females are choosier than males because they need to invest more in child-bearing and child-rearing (Trivers, 1972). Some men manage to sire many children with many different women, and walk away. This may strike us as a morally suspect approach to life, but we should wonder what women see in these men. Women’s choices create the biological inequality of some men becoming Überväter (prolific fathers) whereas others exit the biological world without issue.

The Problem of Valuation

My brief description of the matter is certainly reductive, because other variables are in play. Populations grow or shrink, and there is great cultural as well as inter-individual variation in how persons perceive their own role or their own mission in the drama of human reproduction. Perhaps most irritating is the elusiveness of a good inclusive criterion of what it is to be a good man.

Yet, a reductive approach has the appeal of clarity. Let us, for the moment, accept the view that having children is good. We may note with Malthus (1798) that having too many humans is bad for the planet and for us, but it should be evident that it would also be bad if no one had any children at all—although there would be no one left to bemoan the demise of our species.

So, let us say, with all the due caveats, that having children is better than having none. Given what we have learned, the meaning of this post’s subtitle is clear: “Fathers have more sons on average than sons have sons.” Statistically, it has to be so. So, go forth and multiply – or not.

Implication

Needless to say, what we have learned here about fathers and sons generalizes a fortiori to masters and journeymen, priests and seminarians, professors and graduate students.