Heredity and environment

Every child arrives at school carrying two things: what they inherited from their parents and everything they have experienced since conception. How much each matters has been argued over for more than a century. CTET does not ask you to settle the argument. It asks you to hold one position firmly: development comes from the interaction of heredity and environment, and the teacher is a powerful part of that environment.

This topic sits in the child development part of the CDP syllabus and is linked closely to principles of development and to intelligence and individual differences.

Heredity

Heredity is the passing of traits from parents to children through genes. Genes are segments of DNA carried on chromosomes. Human body cells normally have 23 pairs of chromosomes, one of each pair from each parent. Which genes a child receives is decided at conception.

Heredity influences:

• Physical features: eye colour, blood group, body build, and the potential for height.
• Some aspects of temperament: for example, how active or easily upset a baby tends to be.
• Predisposition to some conditions: certain disorders run in families.
• A range of potential for abilities: heredity does not fix a score; it sets a range within which the environment has a large effect.

Two kinds of twins matter for research. Identical (monozygotic) twins come from one fertilised egg that splits, so they share the same genes. Fraternal (dizygotic) twins come from two eggs and share about half their genes, like ordinary siblings.

Environment

Environment is everything outside the genes that affects development, from conception onward.

Notice that the environment starts before birth. A child's first environment is the womb.

The nature–nurture debate

Watson made a famous claim that, given a dozen healthy infants and control over how they were raised, he could train any of them to become any kind of specialist, whatever their ancestry. In the same passage he admitted he was going beyond his facts. Galton, at the other extreme, coined the word "eugenics". Both positions are now seen as one-sided.

The modern view is interactionist. Heredity sets possibilities; environment decides how far they are realised. Some textbooks express this as development = heredity × environment. The point of the multiplication sign is that if either is missing, nothing develops. A child with the inherited potential to be tall will not reach it without adequate nutrition. A child with strong potential in language will not develop it without people to talk with.

The influence also runs both ways. A lively, curious child draws more conversation from adults, which in turn feeds their development.

What research shows

• Twin studies compare identical and fraternal twins. If identical twins are more alike on a trait than fraternal twins, genes probably play a part.
• Twins reared apart separate shared genes from shared homes.
• Adoption studies compare children with their biological and adoptive parents.

These studies find that both genes and environment matter for traits such as intelligence and personality. They do not show that any child's future is fixed at birth. Adoption studies also show that children moved into richer environments tend to do better at school than their circumstances at birth would suggest.

What this means for a teacher

Teachers cannot change heredity, but they are a large part of the environment for six hours a day.

• Never treat ability as fixed. Labels like "born weak in maths" ignore the role of teaching.
• Reject stereotypes based on caste, class, gender, religion or region. They confuse social disadvantage with inherited ability.
• Make up for gaps. Children whose homes have few books or little time for conversation need richer talk, stories and materials at school.
• Notice physical needs. Hunger, poor eyesight or illness look like "slow learning". Mid-day meals and health check-ups exist for this reason.
• Use the home language as a bridge, since language grows from the child's environment.

How CTET asks this topic

• Direct: "Development is the result of…" (interaction).
• Classification: which factor is hereditary and which environmental.
• Attitude: a teacher's belief or remark, and whether it is justified. These are the questions most often lost.

Worked classroom questions

Scenario 1

A teacher says in the staff room, "Children from that village are not good at studies; it runs in their families." This view is:

(a) correct, since ability is inherited
(b) partly correct, since villages have poor schools
(c) correct, if the children's parents are not literate
(d) incorrect, because it ignores the environment and stereotypes a whole community

Best answer: (d). The remark treats a social disadvantage as an inherited trait and labels children as a group. Option (b) sounds balanced but still accepts the stereotype. Option (c) confuses the parents' schooling with the child's ability.

Scenario 2

Two identical twins were separated at birth and brought up in very different homes. As adults, they are similar in height but differ widely in vocabulary and interests. This shows that:

(a) heredity alone decides development
(b) environment alone decides development
(c) some traits are more strongly influenced by heredity and others by environment
(d) twins do not share genes

Best answer: (c). Height has a strong genetic base when nutrition is adequate. Vocabulary and interests depend heavily on experience.

Scenario 3

A Class 2 child often looks tired and cannot concentrate after the first period. The teacher's first step should be to:

(a) find out whether the child is eating breakfast and sleeping well, and involve the school health staff if needed
(b) complain to the parents about laziness
(c) give the child extra work to build discipline
(d) move the child to the back row

Best answer: (a). Physical environment, including nutrition and sleep, affects attention. Check the cause before judging the child.

Practice MCQs

Q1. Which of these is mainly determined by heredity?

(a) Mother tongue (b) Religious beliefs (c) Food habits (d) Blood group

Q2. Which is part of a child's environment?

(a) School climate (b) Eye colour (c) Genes (d) Chromosomes

Q3. Identical twins are useful in research on heredity because they:

(a) always live together (b) share the same genes (c) have the same teachers (d) are born in the same year

Q4. The modern view of the nature–nurture question is that:

(a) heredity matters more than environment
(b) environment matters more than heredity
(c) both interact to shape development
(d) neither affects intelligence

Q5. A teacher provides storybooks and conversation to children who have few books at home. The teacher is:

(a) changing their heredity (b) favouring some children unfairly (c) wasting time (d) enriching their environment

Q6. The first environment of a child is:

(a) the family (b) the womb (c) the school (d) the neighbourhood

Answers

1. (d). Blood group is inherited; the others are learnt.
2. (a). School climate is environmental.
3. (b). They develop from a single fertilised egg.
4. (c). The interactionist view.
5. (d). Teachers shape the environment, not genes. Extra support for those with less at home is equity, not unfair favour.
6. (b). The prenatal environment affects development from conception.

What to do next

• Draw the environment table from memory, with two examples in each row.
• Write two sentences on why the interaction view is the CTET answer.
• Collect five previous-year questions where a teacher's remark or belief is judged.
• Read how these ideas apply to ability in the guide on intelligence.