Today i learned that Intelligence is heritable and it was a gut punch knowing my parents.
Can anyone clue me in on how it’s expressed or is it a soft cap?
Are highly hifted children anomalies or is it just a good expression of genes?
In: Biology
Not ***exactly*** answering your question here but I wanted to draw your attention to something.
In genetics and evolutionary biology, heritability has a bit different definition than the one we use in normal conversations.
Heritability is the estimate of the portion of ***variance*** observed for the trait (called phenotypical variance) in a ***given population*** that is explained by the variance of the genotypes in this population (called genotypical variance) as opposed to the environmental variance.
So, for exemple, something with a very strong genetic determination may very well have close to none heritability simply because there is close to no genetic variation in the population to begin with (like the number of fingers we are born with.
Think of it like sports. There are some people born with a disability so severe that they will never be able to play sports. There are others who are born with a natural gift that, coupled with hard work, will allow them into the elite echelons of sport. Then there’s the rest of us who fall somewhere along the scale in between. If we work at it we can be good, but never great. No matter where you fall on the scale, hard work is necessary.
There is no such thing as intelligence. The word indicates that people have some sort of overarching cognitive capability but that simply isn’t so. There are lots of cognitive abilities and they are largely uncorrelated. Having a good sense of direction does not imply you’re musically inclined, which does not imply that you’re good at visualization, which does not imply you have good hand-eye coordination, and so on. The total number of distinct cognitive capabilities humans have has never been identified. Heritability of intelligence is just some racist and sexist nonsense dressed up as pseudoscience.
Though genetics plays a part in how intelligent a person can be, no amount of research has shown how much of a role it plays, as there are too many variables that also affect intelligence. So to answer your first question, it’s a soft cap, and can be improved, even in adulthood.
What a lot of people don’t realize is that learning is a skill, and like any skill, it can be improved with practice.
Highly gifted children are a mix of multiple factors, some of which may be attributed to genetics, but it’s not the only factor by far.
Personal anecdote: I’m one of those “gifted” people. Everyone assumes I just automatically know things, like explain it once and I’m an expert. But what nobody sees is that I get up early to study foreign languages, I watch documentaries during my lunch breaks, and I question everything. Most of my Internet search history is “How does..” “How to..” “History of…”, “Etymology of…”, etc. I know a lot because I put the work in, not because of some super genius genes from my parents. My siblings have similar genes, and they’re not gifted. Looking at my wife’s family, same thing, not gifted, except for my sister in law, who has a crazy caffeine addiction due to constantly spending her free time studying and educating herself. Now one could argue that the drive and motivation to self educate may be a genetic factor, but at that point we’re getting pedantic and philosophical.
It is genetic, but has so many genes involved that it wont matter for you. Imagine a man and a woman having 1000 colored balls each. They are average intelligence and half of their balls are red (IQ reducing gene variants) and the other are green (IQ increasing gene variants). Their average 100IQ points is the sum of their good and bad genes.
When they have a child, each parent randomly gives 500 of their gene variants to the child. The child ends up with 1000 colored balls, half from each parent. So the best case is 500 green balls from each parent and a top iq. The worst outcome is all red balls from both parents and probably near the autism spectrum. So if they had 1000 children you would have some geniuses among them.
This is all oversimplified and assumes good education to develop and train the genetic ability and good nutrition to allow proper development.
Blueprints is a great book on the topic:
**Blueprints: Key Evidence on Genes and Intelligence**
*Blueprints* explores how genetics significantly influence intelligence, supported by multiple lines of scientific evidence:
1. **Heritability Studies**:
– **Twin and Adoption Research**: Identical twins, even when raised apart, show similar IQ levels, indicating a strong genetic basis.
– **Heritability Estimates**: Genetics account for approximately 50-80% of the differences in intelligence among individuals, with this influence growing from childhood into adulthood.
2. **Genome-Wide Association Studies (GWAS)**:
– **Genetic Variants**: Numerous genetic markers linked to intelligence have been identified, each contributing a small effect.
– **Polygenic Scores**: Combining these genetic factors can predict aspects of an individual’s cognitive abilities, with accuracy improving as more data becomes available.
3. **Gene-Environment Interactions**:
– **Environmental Influence**: Factors like education and socioeconomic status can enhance or limit the expression of genetic potential for intelligence.
– **Epigenetics**: Environmental conditions can modify how genes related to cognition are expressed, demonstrating a dynamic interplay between genes and surroundings.
4. **Neurobiological Mechanisms**:
– **Brain Structure**: Genetics affect brain development, including neural connectivity and brain volume, which are linked to intelligence.
– **Synaptic Plasticity**: Genes play a role in the formation and adaptability of synapses, essential for learning and memory.
5. **Longitudinal and Cross-Cultural Evidence**:
– **Stability Over Time**: Genetic influences on intelligence remain consistent throughout a person’s life.
– **Cultural Consistency**: Genetic impacts on intelligence are observed across diverse populations, despite different environmental contexts.
*Blueprints* concludes that intelligence is largely shaped by genetic factors, while also recognizing the essential role of the environment in developing cognitive abilities. The book highlights the complex relationship between our genetic makeup and the environments we navigate, emphasizing that both elements work together to shape intelligence.
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