Students survey their own observable traits such as earlobe attachment, tongue rolling, freckles, and handedness to explore patterns of inheritance. By collecting and analyzing class data, they investigate how genetic traits vary in populations and how environment can also influence expression.

1. Provide students with a list of observable genetic traits (e.g., earlobe attachment, tongue rolling, dimples, handedness, freckles, hair texture, hand clasping, red-green colorblindness, hairline shape, PTC tasting).
2. Have each student record their own traits privately.
3. Collect anonymous class data in a table or tally chart.
4. Calculate the percentage of students showing each trait.
5. Compare results to known population averages (e.g., ~75% PTC tasters, ~10% left-handed).
6. Discuss inheritance patterns, noting which traits follow Mendelian rules (dominant/recessive) and which are polygenic or influenced by the environment.

Studying Human Variation - DNA Learning Center:

📄 Human Genetics Survey - Biology Corner: https://www.biologycorner.com/worksheets/geneticsurvey.htm

• Conduct surveys in different classes, age groups, or families and compare frequencies.
• Use Punnett squares to predict trait inheritance in simple cases (e.g., PTC tasting, red-green colorblindness).
• Create family pedigrees for selected traits.
• Compare identical vs. fraternal twins (if available) to study genetic vs. environmental effects.
• Expand the survey to include non-genetic traits (e.g., handedness training in different cultures) to contrast with genetic inheritance.

• Keep survey results anonymous to respect privacy.
• Avoid pressuring students to share traits they are uncomfortable disclosing.
• Emphasize that traits vary naturally and no trait is “better” or “worse.”
• For PTC tasting, only use classroom-safe PTC paper strips.

• Which traits in the survey showed the highest variation? (Answers will vary depending on class data.)
• Why do some traits, like red-green colorblindness, appear more often in males than females? (Because it is an X-linked recessive trait.)
• Which traits matched population averages, and which did not? (Students can compare their results to published statistics.)
• How can both genes and the environment influence traits like freckles or tongue rolling? (Sunlight increases freckles; tongue rolling can sometimes be learned.)
• Why do scientists study large populations rather than small groups when researching traits? (Larger samples provide more accurate and representative data.)