Day 25｜実戦演習④｜教育・心理学
【メイン課題】
以下の英文を 6分〜8分以内 に読んで設問に答えてください。
英文：
The question of whether intelligence is primarily determined by genetics or shaped by environment has been one of the most enduring debates in psychology. Known as the nature versus nurture debate, this discussion has profound implications for education policy, social equality, and our understanding of human potential. While early researchers tended to favor one side or the other, modern science has revealed a far more complex and nuanced picture.
Twin studies have provided some of the most compelling evidence for the role of genetics in intelligence. Identical twins, who share 100 percent of their DNA, tend to have remarkably similar IQ scores even when raised in different households by different families. Studies of twins separated at birth have found that identical twins raised apart have more similar IQ scores than fraternal twins raised together, suggesting a strong genetic component. Researchers estimate that genetics accounts for approximately 50 to 80 percent of the variation in intelligence among individuals.
However, environmental factors play a crucial and often underestimated role in shaping intellectual ability. Children who grow up in stimulating environments with access to books, quality education, and enriching experiences tend to score higher on intelligence tests. Nutrition, particularly in early childhood, has a significant impact on brain development and cognitive function. Exposure to lead, air pollution, and other environmental toxins can permanently impair intellectual development. The Flynn Effect, the well-documented observation that average IQ scores have risen by approximately three points per decade throughout the 20th century, provides powerful evidence that environmental improvements can boost measured intelligence across entire populations.
The interaction between genes and environment is now understood to be far more dynamic than previously thought. A concept known as gene-environment interaction suggests that genetic potential can only be fully realized in supportive environments. A child may have genes associated with high intelligence, but without adequate nutrition, education, and emotional support, that potential may never be fulfilled. Conversely, even children with average genetic endowment can achieve high levels of intellectual performance when provided with exceptional environmental support and educational opportunities.
Epigenetics, a relatively new field of study, has further complicated the nature-nurture debate. Epigenetic changes involve modifications to gene expression that do not alter the DNA sequence itself but can affect how genes function. Research has shown that environmental factors such as stress, diet, and exposure to toxins can cause epigenetic changes that influence cognitive development. Perhaps most remarkably, some epigenetic changes can be passed down from parents to children, meaning that a parent’s experiences can literally affect their offspring’s biology and potentially their intelligence.
The practical implications of this research for education are significant. If intelligence is entirely genetic, then educational interventions would have limited impact, and resources would be better spent identifying and nurturing naturally gifted students. If, however, environmental factors play a substantial role, then investing in early childhood education, nutrition programs, and enriching learning environments could raise intellectual achievement across the population. The current scientific consensus supports the latter view, suggesting that while genetics sets a range of potential, the environment determines where within that range an individual’s abilities will fall.
設問：
（1）双子研究が示す遺伝の役割について本文に基づいて説明しなさい。
（2）「フリン効果」とは何か、また環境の重要性をどう示しているか説明しなさい。
（3）「エピジェネティクス」が自然vs養育の議論をどう複雑にしたか説明しなさい。
（4）本文の内容と一致するものを全て選びなさい。
a. 一卵性双生児は別々の家庭で育てられてもIQが類似する傾向がある
b. 遺伝が知能の変動の約50〜80%を説明すると推定されている
c. 20世紀を通じて平均IQスコアは10年ごとに約3ポイント上昇した
d. エピジェネティックな変化が親から子に遺伝することはない
e. 現在の科学的合意は、環境が知能の発達に大きな役割を果たすことを支持している
（5）この文章全体を80字以内で要約しなさい。
模範解答を見る ▼
【模範解答】
各段落のキーワードメモ：
– 第1段落：自然vs養育の議論の紹介
– 第2段落：遺伝の証拠（双子研究）
– 第3段落：環境の証拠（フリン効果など）
– 第4段落：遺伝と環境の相互作用
– 第5段落：エピジェネティクス
– 第6段落：教育への実際的示唆
設問の解答：
（1）一卵性双生児（DNA 100%共有）は、別々の家庭で育てられても非常に類似したIQスコアを示す。出生時に分離された一卵性双生児は、一緒に育てられた二卵性双生児よりもIQが類似しており、知能に強い遺伝的要素があることを示唆している。
（2）フリン効果とは、20世紀を通じて平均IQスコアが10年ごとに約3ポイント上昇したという観察結果。人間の遺伝子構成は数十年で大きく変わらないため、この上昇は環境の改善（栄養、教育、生活条件の向上など）によるものと考えられ、環境が知能に重要な影響を与えることを示している。
（3）エピジェネティクスは、DNA配列自体を変えずに遺伝子の発現に影響を与える修飾を研究する分野。ストレスや食事などの環境要因がエピジェネティックな変化を引き起こし、認知発達に影響する。さらに一部の変化は親から子に受け継がれ得るため、親の経験が子の生物学に影響する可能性がある。これにより「遺伝」と「環境」の境界が曖昧になっている。
（4）正解：a、b、c、e
– a：本文 “remarkably similar IQ scores even when raised in different households” → 正解
– b：本文 “approximately 50 to 80 percent” → 正解
– c：本文 “approximately three points per decade throughout the 20th century” → 正解
– d：本文 “some epigenetic changes can be passed down from parents to children” → 遺伝すると述べている → 不正解
– e：本文 “The current scientific consensus supports the latter view” → 正解
（5）要約例：知能は遺伝と環境の複雑な相互作用で決まり、エピジェネティクスが両者の境界をさらに曖昧にしている。環境が重要な役割を果たすという科学的合意は早期教育への投資を支持する。（80字）
ポイント（速読のコツ㉕）：
– 学術的な文章は 「定義→証拠A→証拠B→統合→応用」 のパターンが多い。最初に概念の定義を掴み、最後に結論（応用・示唆）を確認すれば、中間段落は証拠の紹介だと予測できる。この構造を意識しながら読むと、英文全体を効率的に理解できる。
【練習問題】以下の英文を6分〜8分以内に読み、設問に答えなさい。
英文：
Growth mindset theory, developed by Stanford University psychologist Carol Dweck, has become one of the most influential concepts in modern education. According to Dweck’s research, people generally fall into two categories based on their beliefs about intelligence and ability. Those with a “fixed mindset” believe that intelligence is an innate trait that cannot be significantly changed. Those with a “growth mindset,” on the other hand, believe that intelligence and abilities can be developed through effort, learning, and persistence.
Dweck’s studies found that mindset significantly affects how students respond to challenges and setbacks. Students with a fixed mindset tend to avoid difficult tasks because failure would suggest a lack of natural ability. When they do encounter obstacles, they are more likely to give up quickly. Growth mindset students, by contrast, embrace challenges as opportunities to learn and view failure as a natural part of the learning process. They persist longer in the face of difficulty and ultimately achieve higher levels of performance.
The concept has been widely adopted in schools around the world. Teachers are encouraged to praise effort and process rather than innate talent, using phrases like “you worked really hard on that” instead of “you’re so smart.” Schools have implemented programs designed to teach students about brain plasticity and the idea that the brain grows stronger through practice and learning, much like a muscle grows through exercise.
However, the growth mindset concept has faced criticism from researchers who argue that it has been oversimplified and overapplied. Several large-scale studies have failed to replicate Dweck’s original findings, raising questions about the size and reliability of mindset effects on academic achievement. Critics also point out that telling struggling students to “try harder” without providing concrete strategies and support can actually be counterproductive, increasing frustration and self-blame.
Dweck herself has acknowledged some of these concerns, noting that growth mindset has sometimes been misunderstood and misapplied. She emphasizes that a true growth mindset is not simply about effort but about using effective strategies, seeking help when needed, and learning from mistakes. She also warns against what she calls “false growth mindset,” in which people claim to have a growth mindset but continue to react to challenges with anxiety and avoidance.
設問：
（1）「固定マインドセット」と「成長マインドセット」の違いを説明しなさい。
（2）成長マインドセット理論への批判を2つ挙げなさい。
（3）この文章全体を80字以内で要約しなさい。
練習問題の解答を見る ▼
【練習問題 解答】
設問の解答：
（1）
– 固定マインドセット：知能は生まれ持った特性であり大きく変えられないと信じる。困難なタスクを避け、障害に直面するとすぐに諦める傾向がある。
– 成長マインドセット：知能や能力は努力・学習・粘り強さによって伸ばせると信じる。困難を学びの機会と捉え、失敗を学習の自然な一部と見なす。
（2）
– ①大規模な追試でDweckのオリジナルの知見を再現できず、マインドセット効果の大きさと信頼性に疑問が呈されている。
– ②苦戦している生徒に具体的な戦略やサポートなく「もっと頑張れ」と言うことは逆効果になり得る。
（3）要約例：成長マインドセット理論は教育に広く取り入れられたが、効果の再現性への疑問や過度な単純化への批判があり、Dweck自身も正しい理解と適用の重要性を強調している。（78字）