Unit 9 of 12 · Your body and brain · about 3 weeks

Genetics and Epigenetics: What do my genes actually do?

By · Published

"Your lifestyle changes your genes" is a popular slogan and it is wrong in a way that slides easily into pseudoscience. The accurate version is more interesting: your DNA sequence stays the same, but cells switch genes on and off, and some of those switches respond to the environment.

Build the foundation first, then regulation, then epigenetics. The order is the whole point.

Same instructions, different cells

  1. Show a picture of a nerve cell and a skin cell. Ask whether they have the same DNA. (Essentially yes.)
  2. So why do they look and act so differently? Because each uses a different set of the same instructions.
  3. Compare it to a cookbook every cell owns: a bakery and a soup kitchen own the same book but cook different recipes.

Core ideas

  • DNA → genes → proteins → cells → traits.
  • A cell does not use every gene at once; gene regulation decides which genes are used, when and how much.
  • Epigenetics: molecular marks that change whether or how strongly genes are expressed without changing the DNA sequence (the National Human Genome Research Institute's definition).
  • Genes and environment interact to produce traits (phenotype); neither acts alone.

Activities

Bead DNA with tags

Build a DNA strand from colored beads or LEGO. Add removable tags: red = gene strongly expressed, yellow = weakly expressed, black = silenced. Move the tags and show that the sequence never changes but the cell's behavior does.

Twin plants

Grow cuttings from the same plant (genetically near-identical) under different light, water or nutrients. Measure and photograph them weekly. Same genes, different environment, different plant.

Strawberry DNA extraction

Extract visible DNA from strawberries with dish soap, salt and cold rubbing alcohol (adult handles the alcohol).

One lesson, three outputs

Grades K–2 (ages 5–8)

"Every living thing has instructions inside it." Extract strawberry DNA and grow the twin plants with drawings each week.

Grades 3–5 (ages 8–11)

Build the bead model, learn the DNA → protein → trait chain, and graph the plant experiment.

Grades 6–8 (ages 11–14)

Explain gene regulation and epigenetics accurately, write a lab report on the plant experiment, and critique a misleading health headline about "changing your genes."

The family question

Did the instructions change, or how they were used?

Thinking Journal prompt

What surprised me about how genes work? What headline would I now be suspicious of?

Getting it right

Avoid saying lifestyle "changes your DNA" or that epigenetic effects are simply passed to your children; inheritance of epigenetic marks in humans is limited and still debated. Say instead that the environment can influence how some genes are used.

Free resources