Twin

High school (ages 12+)
Human Body

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/twin

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the genetic similarity (monozygotic)?Approximately 100% shared DNA
2. What is the genetic similarity (dizygotic)?Approximately 50% shared DNA, similar to non-twin siblings
3. How do identical twins form?Identical twins start from one fertilized egg that splits into two embryos before the 10th day after fertilization. Because they come from the same egg, they have almost the same DNA.
4. Can twins be different genders?Only fraternal (non‑identical) twins can be different genders. Identical twins always share the same gender.

Concordance Rate: The probability that if one twin has a particular trait or condition, the other twin will also have it.
Heritability: A statistical estimate of the proportion of variation in a trait within a population that is due to genetic factors.
Epigenetics: The study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself.