11.6 Biological Approaches — Was Your Personality Decided Before Birth | Psychology 2e

• Understand how evolution drives personality traits and individual differences.
• Learn how evolutionary 'budgets' influence personality traits like impulsivity.
• Discover how showing off is an ancient evolutionary tactic to signal worth.
• Explore how identical twins raised apart show strikingly similar personalities.
• Clarify that heritability describes population variation, not individual gene contribution.
• Learn how epigenetics dictates whether genetic instructions are expressed or ignored.
• Understand early infant personality categories and their biological basis.
• Discover how infant temperaments evolve into adult dimensions of reactivity and self-regulation.
• Understand that biology sets a baseline, but environment drastically shapes trait expression.
• Up next in “Psychology 2e — Full Course (OpenStax) | Intro Psychology Lectures”11.7 Trait Theorists — From 4,500 Words to the OCEAN Model | Psychology 2e

How much of who you are was shaped before you ever experienced the world? This lesson explores the biological approach to personality, examining how inherited predispositions, genetics, and early temperament interact with environment to make us who we are. Drawing from Section 11.6 of OpenStax Psychology 2e, the discussion covers everything from evolutionary psychology to the landmark Minnesota Study of Twins Reared Apart. In this video: • Evolutionary psychology and David Buss's Life-History Theory — how humans subconsciously budget energy between growth, mating, and parenting • Costly Signaling Theory — why showing off on a date or exaggerating to impress a friend may be an ancient survival tactic • The Minnesota Study of Twins Reared Apart (1979–1999): 350 twin pairs reveal heritability ratios above 0.50 for traits like leadership, fearfulness, and obedience to authority • Why heritability doesn't mean one gene controls one trait — multiple genes work together like a complex architectural blueprint • Epigenetics as the 'foreman on the construction site,' controlling whether genetic instructions are actually expressed • Thomas and Chess's three infant temperament categories — easy, difficult, and slow to warm up — and their biological basis • Reactivity and self-regulation: how early temperament evolves into two key dimensions of adult personality #OpenStax #Psychology #Personality #BehavioralGenetics #EvolutionaryPsychology 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