Biology 101: Epigenetics and identity !

Imagine sitting across from your identical twin—or clone—at age 50, only to realize you’ve become completely different people. Through an accessible metaphor involving tattoos, circuses, and tater tots, the lesson introduces a powerful idea: while your DNA may stay the same throughout your life, how your genes express themselves is shaped by everything from stress to diet to your grandmother’s childhood. You’ll explore how gene regulation works, and why it challenges the idea that we’re simply “born this way.”

Watch the SciShow video (9 minutes) then answer the following interactive questions.

Sample answers:

Question 1:

Strong answer:

The clone metaphor is effective because it shows how two genetically identical people can turn out very differently based on how their environments influence gene expression. For example, the clone grows up with poor nutrition and more stress, while the narrator lives a more stable and well-fed life. These differences could lead to more methylation on certain genes in the clone’s body—such as genes related to growth or immune function—effectively silencing them. At the same time, the narrator’s high-stress job could tighten histone structures around stress-response genes, reducing their ability to function properly. These kinds of epigenetic changes don’t alter the DNA itself, but they do change how active certain genes are. As a result, the clone might be shorter or more physically fit, while the narrator might have higher risk for health conditions like heart disease. The metaphor helps make these invisible molecular changes visible—it shows that the “software” of gene expression is shaped by experience, and that identity is a product of both genetics and life history.

Weak answer:

The metaphor is good because it shows how people can be different. It makes it funny and easier to learn. The clone does circus stuff and the regular person doesn’t. That’s why they’re different. It helps us see that genes are not everything and people are who they are.

Question 2:

Strong answer:

In my family, we tend to stay up late and working or studying into the night. My parents did it, and now I do too—even when I know it messes with my sleep. After watching the video, I wonder if this habit of irregular sleep could affect gene expression related to stress or metabolism over time. Epigenetically, it makes sense that a long-term pattern like this could cause changes in how certain genes are expressed—and possibly influence future generations if those tags are passed on.

Weak answer:

My family eats late at night and I do too. It might affect my kids in the future. Maybe their genes will be different because of that.