Across
- 4. Fraternal Twins
- 6. Identical Twins
- 8. The side of the debate which supports genetic ideas
- 9. Conducted a twin study
Down
- 1. The psychologist who proposed XYY theory
- 2. Type of study to investigate genetics
- 3. Theory which involves having an extra chromosome
- 5. The rate used to describe the similarity between two twins
- 7. Unit of DNA