Is 126 a Good IQ Score? And Where Did It Come From?

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What does an IQ of 126 actually mean?

IQ scores are standardised so that the population mean is 100 and the standard deviation is 15. A score of 126 is 26 points above the mean, or about 1.73 standard deviations. That places you in the upper half of the Superior band, which runs from 120 to 129 and is relabelled Very High in the WISC-V and WAIS-5.

For orientation against the reference data: doctoral degree holders average around 115, professional degrees around 114, master's degrees around 112. You are eleven points above the doctoral mean. The most cognitively demanding occupational group means, in theoretical physics and mathematics research, sit at roughly 125 to 130, and you are inside that band.

The exact percentile for an IQ of 126

Using the standard normal distribution, an IQ of 126 maps to the 95.85th percentile:

In a secondary school of 1,000 pupils, around 42 would be expected to reach 126. In a 100-person office, four.

Where does a score like this come from?

The evidence here is good, and the shape of it surprises most people.

Twin and adoption studies estimate how much of the variation in IQ within a population tracks genetic variation. The headline finding, summarised by Bouchard (2013) as the Wilson effect, is that this proportion rises with age. It reaches roughly 0.80 by ages 18 to 20 and stays at about that level through adult life. Over the same period, the influence of the shared family environment falls to around 0.10.

That is the opposite of what most people expect. The intuition is that childhood shapes you and the effect persists. What the data shows is that the household you grew up in has a substantial effect on your measured IQ as a child which then fades, while the genetic contribution becomes more visible as you get older and increasingly select your own environments.

Three things this does not mean, all of which get claimed anyway:

• It does not mean your score is fixed. Heritability describes where variation comes from under the conditions studied. It is not a measure of how changeable something is. Height is highly heritable and average height still rose dramatically with nutrition.
• It does not apply to you individually. A heritability of 0.80 is a statement about variance across a population. There is no meaningful sense in which 80% of your 126 is genetic.
• It says nothing about differences between groups. Within-group heritability carries no implication for the causes of between-group differences. This is a well-established point in the field and it is routinely misrepresented.

One scope caveat worth stating: these estimates come overwhelmingly from studies in wealthy industrialised democracies. Where environments vary far more widely, shared environment tends to account for more and heritability estimates come out lower.

Will your children score like you?

This is the question that usually follows, and it has a specific answer with a specific name. They will tend to score above average and closer to the population mean than you are. Francis Galton identified the pattern in the nineteenth century studying height, and called it regression toward the mean.

Reed and Rich (1982) put numbers on it for IQ using over 2,000 parent-offspring pairs. The regression coefficient of a child's IQ on the mid-parental average was about 0.61. Where the mid-parental average was above 114, it was closer to 0.50.

Applied to your score, roughly: if two parents both scored 126, the expected average for their children lands somewhere in the mid-110s. Still clearly above average, and noticeably below the parents. If only one parent is at 126 and the other is nearer 100, the expected value drops further, toward the low 110s.

Two cautions on reading that, because this is exactly the sort of figure that gets over-interpreted. It is an expected average across many families, and the scatter around it is large: siblings raised together routinely differ by more than ten points. And it cuts the other way too, which is the part people forget. Parents well below the mean tend to have children closer to it from the other side. Regression toward the mean is not a statement about decline; it is what happens whenever a trait is measured imperfectly and influenced by many partly independent factors.

How much to trust a single score of 126

The WAIS-IV has a test-retest reliability of about 0.96 for Full Scale IQ, and the standard error of measurement is typically plus or minus 3 to 5 points. A 126 would be reported clinically with a confidence interval of roughly 121 to 131.

Two things are worth checking if your score came from a proper assessment. Whether your index scores were uneven, which can make the Full Scale figure a poor summary, is covered in our guide to an IQ of 127. And how age-norming works, which explains why the number stays stable across decades, is covered in our guide to an IQ of 128.

Can you join Mensa with an IQ of 126?

Not on that score. Mensa requires a score at or above the 98th percentile on a supervised standardised test, which is IQ 130 on the Wechsler scale and 132 on older Stanford-Binet scales. You are four points short.

Four points is inside the standard error of measurement, so a single supervised retest could plausibly land above the line. Repeated attempts are a different matter, since practice effects inflate scores and a result obtained that way is measuring familiarity. The scale question, which is the most common source of confusion about what Mensa actually requires, is covered in our guide to an IQ of 132.

What to keep in mind about an IQ of 126

A few things worth knowing so you can read your score accurately.

• Heritable does not mean fixed. The Wilson effect describes where variation in a population comes from, not how malleable any individual's ability is. Confusing the two is the most common error in this area.
• Your family environment mattered, and then it stopped. Shared environment shows a real effect on children's scores that fades to almost nothing by adulthood, which is worth knowing if you are drawing conclusions about your upbringing from your score.
• Regression toward the mean is not decline. Expect children closer to 100 than you are, and expect wide scatter. The same mathematics pulls upward from below the mean.
• It measures one thing. IQ captures the general factor behind reasoning and problem-solving, which is important and well studied. Creativity, judgement, emotional intelligence and persistence shape outcomes too, and a 126 is silent on all of them.

The bottom line on IQ 126

An IQ of 126 is a strong score. You are at the 96th percentile, roughly 1 in 24, eleven points above the average doctorate holder, and inside the band containing the highest measured occupational group means. Four points separate you from the gifted threshold, which is inside the measurement error on most tests.

On where it came from: by adulthood, roughly 0.80 of the variation in IQ across a population tracks genetic variation, while the shared family environment falls to about 0.10. That is a statement about populations, not about you, and heritable has never meant unchangeable.

On whether it is passed on: children of parents at this level tend to land above average and closer to 100 than their parents, with wide variation around that expectation. That is regression toward the mean, it has been understood since Galton, and it is neither a decline nor a prediction about any particular child.

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