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This lesson explores how genes and environment interact to shape human behavior, traits, and vulnerability to psychological disorders — and why DNA alone never tells the full story. Drawing from Section 3.1 of OpenStax Psychology 2e, the discussion moves from the paradox of sickle-cell anemia and Darwinian evolution all the way to cutting-edge epigenetics and a landmark adoption study on schizophrenia. By the end, you'll understand why human biology is less a fixed blueprint and more a dynamic, ongoing conversation between inheritance and experience. In this video: • Why the sickle-cell mutation persisted in human populations — and how it doubles as protection against malaria • The difference between evolutionary psychology (universal, ancient behavioral patterns) and behavioral genetics (individual differences today), and why twin and adoption studies matter • Genotype vs. phenotype vs. alleles explained — with cleft chin and PKU as concrete examples of dominant and recessive inheritance • Why polygenic traits make race a biologically weak construct, and why distinguishing ancestry from race has life-or-death medical consequences • Three frameworks for gene-environment interaction: Range of Reaction, genetic-environmental correlation, and epigenetics • How epigenetic 'chemical tags' can silence specific genes in response to stress, diet, or trauma — without changing the underlying DNA sequence • The Tienari (2004) schizophrenia adoption study: high genetic risk + disturbed family environment produced a 36.8% disorder rate vs. 5.8% in a healthy environment #OpenStax #Psychology #Genetics #Epigenetics #BehavioralGenetics OpenStax Content adapted from "OpenStax Psychology 2e", by OpenStax licensed under CC BY 4.0. Content based on Web Version: Apr 23, 2026. Read the textbook online https://openstax.org/details/books/psychology-2e Music first girl talking to me. by ikkun (ex. Barradeen) | https://soundcloud.com/ikkunwastaken Royalty Free Music by https://www.free-stock-music.com Creative Commons / Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0) https://creativecommons.org/licenses/by-sa/3.0/deed.en_US
Answer each question based only on what was presented in the video lesson. No outside knowledge is required — all answers can be found in the video.
Answer each question using what you learned in the video. Questions progress from recall and understanding to application and analysis — take your time with the later ones.
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