identical twin
B2Neutral to formal; common in both everyday and scientific contexts.
Definition
Meaning
One of two siblings born from the same pregnancy who developed from a single fertilized egg that split, resulting in individuals who share the same genetic makeup.
Used metaphorically to describe two people or things that are extremely similar or indistinguishable in appearance, nature, or function.
Linguistics
Semantic Notes
The term is specific to monozygotic twins. It is often contrasted with 'fraternal twin' (dizygotic). The metaphor implies near-perfect duplication.
Dialectal Variation
British vs American Usage
Differences
No significant lexical differences. Spelling of related words may differ (e.g., 'recognise' vs. 'recognize').
Connotations
Identical in both varieties.
Frequency
Equally common in both varieties.
Vocabulary
Collocations
Grammar
Valency Patterns
[Subject] + be + identical twin(s) + (of/to [Person])[Person] + have + an identical twinVocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “(like) two peas in a pod (similar idiom for resemblance)”
Usage
Context Usage
Business
Rare. Used metaphorically: 'The two product lines are identical twins in terms of market performance.'
Academic
Common in genetics, psychology, and medical research: 'The study compared cognitive abilities in identical twins raised apart.'
Everyday
Common when discussing family or describing uncanny resemblance: 'I didn't know you had an identical twin!'
Technical
Standard term in biology and medicine for monozygotic twins.
Examples
By Part of Speech
verb
British English
- The fertilised egg can twin early in development.
- They are twinned in every aspect of their appearance.
American English
- The fertilized egg can twin early in development.
- They are twinned in every aspect of their appearance.
adverb
British English
- They are identically twinned.
- The children were dressed identically, like twins.
American English
- They are identically twinned.
- The children were dressed identically, like twins.
adjective
British English
- They have an identical-twin sister.
- The phenomenon is studied in identical-twin research.
American English
- They have an identical-twin sister.
- The phenomenon is studied in identical-twin research.
Examples
By CEFR Level
- She is an identical twin.
- The two girls look the same. They are identical twins.
- My brother is an identical twin, so he and his brother look exactly alike.
- It is sometimes hard for teachers to tell identical twins apart.
- Studies of identical twins raised separately provide unique insights into the nature versus nurture debate.
- Despite being identical twins, they have developed quite different personalities.
- The genetic concordance rate for the condition was significantly higher in monozygotic, or identical, twins than in dizygotic pairs.
- The defendants, who were identical twins, presented a unique challenge for the prosecution's forensic evidence.
Learning
Memory Aids
Mnemonic
Think: 'IDENTical' = they have the same 'IDENTity' or DNA.
Conceptual Metaphor
IDENTICAL TWINS ARE A SINGLE SPLIT ENTITY / PERFECT DUPLICATES.
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid direct calque 'идентичный близнец' in formal contexts; the standard term is 'однояйцевый близнец'.
- The English term is a fixed compound noun; word order is crucial ('identical twin', not 'twin identical').
Common Mistakes
- Using 'identical twin' to refer to any twins who look alike (must be monozygotic).
- Confusing 'identical' (genetically the same) with 'similar'.
Practice
Quiz
What is the key biological fact about identical twins?
FAQ
Frequently Asked Questions
Yes, with extremely rare exceptions due to genetic mutations, identical twins are always the same gender because they originate from a single zygote with a single set of sex chromosomes.
Identical (monozygotic) twins come from one fertilized egg that splits, sharing the same DNA. Fraternal (dizygotic) twins come from two separate eggs fertilized by two separate sperm, making them genetically like ordinary siblings.
Yes. While their DNA is identical, fingerprints are influenced by environmental factors in the womb, so even identical twins have unique fingerprints.
It is primarily a compound noun (e.g., 'She is an identical twin'). It can also function attributively as a compound adjective before another noun (e.g., 'an identical-twin study').
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