We often hear people saying that blue eyes are hereditary in our family. Baldness in men and certain diseases like Down’s syndrome is inherited. How do we inherit characters or diseases? Do genes or surroundings shape one’s personality?
The Gene- The basis for Hereditary
A gene is a tiny section along with the DNA with instructions that encodes the synthesis of a specific product, usually a protein, that triggers a particular action. The basis of inheritance is the transmission of genes from parents to off-springs during the process of reproduction.
Understanding DNA structure
Chromosomes are present inside the nucleus of cells. Long strands of DNA are tightly wrapped around the histone proteins to form chromosomes. DNA is made up of long strands of double helix structures containing crucial genetic information. If the DNA from all the cells are taken out and lined up, end to end, it will form a fragile strand 6000 million miles long. Every cell has the same DNA but varies with person to person.
Why Mutations? Alleles evolution through Mutation
The instructions in the DNA are copied and converted into a functional protein during the process of gene expression. Reports indicate that genetic expression can be influenced by various social factors as well as environmental factors from light, temperature to exposure to chemicals.
The sequence of nucleotides in a gene can differ between copies of the same gene. A gene can acquire a mutation in their sequence while copying, leading to a different variant, known as alleles. It consists of a sequence of combinations of nucleotide bases, ACGT. Genes evolve due to the survival of the fittest and genetic shift of the alleles.
Role of Alleles
These small differences in the sequence of DNA in alleles contribute to each person’s unique physical features. Alleles, as well as gene-environment interactions, influence most of the traits. Genotype refers to the genetic characteristics of a person. A phenotype refers to the observable physical characteristics of a person.
Nature or Nurture?
The phrase “Nature and Nurture” was first coined by Sir Francis Galton. The relationship between behaviour and genetics dates back to the work of Galton. Nature and nurture work in tandem to create one’s personality. All behaviour is due to the overlapping of heredity and environment.
Studies to understand Nature or Nurture
Adoption studies and twins studies have thrown more light to understand the debate.
Identical twins share the same genotype means they have similar genetic make-up. Twins raised apart tend to be similar in intelligence, life experiences and life events. They, when raised in different environments, exhibited different behaviour.
If a child is being raised by parents who are genetically different from his/her biological parents, the child shows close similarity in behaviour with the adoptive parents or siblings.
Wrapping it up
Adoption studies support the influence of the environment on behaviour strongly. Twin studies support the influence of genes on behaviour. But, nurture or nature, which side dominates is still ambiguous.