Behavioural Genetics

What is Behavioural Genetics?

Behavioural genetics is the study of genetic and environmental influences on animal or human behaviour. The inheritance of behavioural traits has been studied by the geneticists.

Methods of Study of Behavioural Genetics

The effect of genetic and environmental factors on human behaviour have been studied using quantitative genetic methods. The genes responsible for a particular genetic influence are observed by molecular genetic methods. The research has been carried out on both humans and animals but the researches on animals have given more accurate results. This is because the environment and genes both can be controlled in the laboratory. The following experiments were performed to study the genetic and environmental influences on behaviour in humans and animals:

In Animals

  • The siblings were mated for several generations. The offsprings obtained were highly similar genetically. The genetic influence on behaviour can also be observed by comparing the behaviour of different inbred strains brought up in the same laboratory environment.

  • Selective breeding is another method for selecting genetic influences. In this, organisms with high and low extremes of a trait are bred for several generations. These methods have been applied to a number of animal behaviours and have provided proves for the influence of genes on behaviour, especially in learning and behavioural responses to drugs.

Also read: Acquired and Inherited Traits

In Humans

  • Twin method is used to study the genetic influence on behavioural differences. The environment and the genes cannot be controlled or manipulated in humans. Monozygotic twins or identical twins are genetically the same because they come from the single fertilized egg. They are clones of each other. The dizygotic twins that come from different fertilized eggs are half genetically similar like any other sibling born at different times. With reference to the fact that the behaviour is influenced by the environmental factors, the dizygotic twins should be exactly similar because they are brought up in the same environment by the same parents at the same time. If the behaviour is influenced by genes, then the dizygotic twins should be less similar than the monozygotic twins. For eg., the risk of one twin being schizophrenic if the other one is already suffering from the condition is 45% in monozygotic twins and 15% in dizygotic twins. Also, the intelligence assessed by the IQ tests is 0.85 in monozygotic twins and 0.60 in dizygotic twins. However, the twin method was strictly defended.

  • Adoption method was also adopted in which the child is owned and brought up by someone who is not the biological parent of the child. A study proved that children with schizophrenic biological mothers when adopted far away from their biological parents had a 10% chance of becoming schizophrenic compared to the children brought up by the schizophrenic mothers.

Researches are being carried out to know the influence of genes and environment on the behaviour of animals and human beings.

Also read: Heredity

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