# Childhood experiences & epigenetics

> IB Psychology · IB Psychology 2027 First Assessment
> Source: https://www.owlsprep.com/study/ib-psychology-hd-childhood-experiences-and-epigenetics/

The role of childhood experiences in the development of self.

## Learning objectives

- The role of childhood experiences in the development of self.

## How often is this tested?

Based on OwlsPrep's analysis of official CIE IB_PSYCH P2 past papers (2019–2025): **Childhood experiences & epigenetics** appears **13 times** in the last 7 years — **4.5%** of all P2 questions (13 of 288).

Most-tested forms: Essay: Discuss (22 marks) (11), Essay: To what extent (22 marks) (2).

## Core concept

Early childhood experiences — especially the quality of care and exposure to adversity — can leave lasting marks on how a person develops. One well-studied route is epigenetic: experience can chemically tag genes (for example by adding methyl groups) so that they are expressed more or less, altering systems such as the stress response without changing the DNA sequence itself. This gives a biological pathway by which early nurture or hardship shapes the adult self, while still interacting with later experience.

## Key studies

IB Psychology answers must be supported by named studies. Learn these to cite as evidence:

**Weaver et al. (2004)** — Rat pups given little maternal nurturing showed increased methylation of the glucocorticoid-receptor gene and became more stress-reactive adults; well-nurtured pups showed the opposite. — *An animal model of the mechanism — early experience biologically programming the later stress response.*

**McGowan et al. (2009)** — People abused in childhood who later died by suicide showed the same increased glucocorticoid-receptor methylation in the hippocampus found in the rats. — *Extends the mechanism to humans — early adversity leaving a molecular trace linked to the adult self.*

## Evaluation (AO3)

**Strength — a concrete cross-species mechanism** — The rat model (Weaver) and the human data (McGowan) converge on the same gene and stress system, giving a rare, specific biological account of how childhood experience becomes embedded.

**Limitation — correlational in humans and not deterministic** — The human evidence is post-mortem and correlational (abuse co-occurs with much else), and outcomes are not fixed — resilience and later care can shift trajectories, so early experience shapes but does not seal the self.

## Scope

> **note**
>
> How early experience shapes the later self, via epigenetics, is the focus. The genetics concept is BIO_6 and the interaction model is BIO_5; critical-period effects on the brain are HD_1.

## Common pitfalls

- **Wrong:** A bad childhood, or an epigenetic 'scar', permanently and inevitably determines the adult.
  - Why it fails: A frequently penalised misconception in IB Psychology exams.
  - Correct: Early experience raises or lowers risk through real biological pathways, but the effects are probabilistic and partly reversible — resilience, later relationships and care matter (McFarlane found family functioning predicted outcomes more than direct trauma exposure).

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