Role of Genetics and Family Environment in Intelligence


Researchers are always keen to find the role heredity and family environment play in the intelligence of a human being. Research studies around the world have shown mixed viewpoints in this regard.

This has actually been one of the most debatable issues seen in the history of psychology and has maintained to be the topic of debate even to this date. The real problem is the dispute over the nature of intelligence as a whole. Along with the dispute at the elementary nature of intelligence, psychologists are surfing a large amount of time and energy to find out the various factors that have an impact on an individual’s intelligence level.

There is a long debate of ‘Nature VS Nurture’ going on for a long time. There are mixed research views in this regard. Some psychologists give nature high weightage on the nurturing factors while other claims that there is an immense role of environment in the personality development of a being.

The Debate of Nature or Nurture


Nature vs nurture has been one of the most philosophical issues present in the field of psychology. Nature includes all the genetic and heredity factors ranging from physical appearances to various personality-related factors.

On the other hand, nurture includes all the environmental factors that have an impact on us. For instance, early childhood, experiences associated with childhood, the impact of practices through which we are raised, the quality of our social relationships, and the culture we live in.

Psychologist Francis Galton claimed that intelligence is the result of heredity and genetic factors. He even added that intelligent people should get married and have babies, while less intelligent people should avoid getting married. And even if they get married, they should not reproduce. This statement sparked a large number of issues in society.

Today, the majority of experts and psychologists believe that both nature and nurture shape the intelligence of a person. Genetic factors plus environmental factors influence behavior and personality development.

Few psychologists have also added that genetic factors intermingle with environmental factors and they do not work independently.

Research findings on the role of Genetics in Intelligence


Today, psychologists claim that both heredity and the current family environment play their part in intelligence. The point of concern now is how much role each factor plays.

A research was conducted on twins and it found out that IQ ( is associated with genetics. This study found that genetics play a bigger role in intelligence as compared to environmental factors.

Psychologists have highlighted that the genetic role of intelligence does not depend on a single “Intelligence Gene”. Rather, intelligence is the byproduct of a large number of genes interacting with one another. Further research advancements suggested that inheritance and environment interact with one another to decide exactly how inherited genes are expressed.

Studies have shown that the IQ scores of identical twins are similar to one another as compared to those of fraternal twins.

It is also shown that the siblings who are raised in the same environment have more parallel IQ levels as compared to adopted children raised in the same household. This research successfully highlighted the role of genetics in the intelligence level of a being.

Along with hereditary characteristics, other biological factors are also important such as parental malnutrition, parents’ contact to destructive substances, and parental age. These factors also play role in the IQ levels.

Few studies have also found that those who have low IQ levels have more chances to report criminal activities that can bring serious consequences including physical injuries, emotional trauma, or loss of physical property or assets.

Research findings on the role of Family Environment in Intelligence


Some studies in the developed countries have found that there are some family effects on the IQ of a child but this correlation approaches zero by the time an individual reaches adulthood.

After adulthood, adopted children become dissimilar in terms of their IQ levels while the real and full siblings still show some correlation (0.6). Twin studies reinforced that identical twins raised separately have more similarities as compared to fraternal twins.

But the important point here is to remember that such studies did not cater to the emotional and social effects associated with the whole process of adoption.

Research has also highlighted that the IQ of a child is also determined by the socio-economic status of the parents. Socio-economic status includes the income of the parents, their educational background, their occupational status, and their overall lifestyle.

Further research development has added that some other characteristics also play a vital role such as IQ level of a parent, quality of instructions given by parents to their child, parents nurturing practices, family structure (Two parents vs divorced or never-married mother), total number of children in the family, nutrition, mother’s age at the time of the birth of the child and child’s weight.

Final Thoughts


There is a long debate on the role of genetics and environment on the intelligence of a child. Few research studies have claimed that the genetic makeup of an individual cannot be overlooked when assessing intelligence. Genetics plays an important role in determining the IQ level of a child.

On the other hand, few pieces of research have shown that external factors separate from genetics and heredity also play a part in the intelligence of a being. The family environment in which the child is raised also plays an important part.

Recent research developments have highlighted that genetics and external environmental factors interact and intermingle with each other shaping the intelligence of an individual. An individual is a byproduct of his or her genetic makeup and the environment in which he or she is raised.

Family trends such as low socioeconomic status have an impact on the IQ of the children. In order to change that, there is a need to look at the programs and measures that can improve family behaviors, or at least, improve parental behavior to infants.