chapter -4 Behavioural Genetics

Peopleadoptedinwhichcharacteristicsarecomparedbothbetw

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Unformatted text preview: ingthesamegenesasparents Psych 1000 My Notes Page 22 - - - - Offspringhasa50%chanceofhavingthesamegenesasparents 50%chanceofhavingthesamegenesasbrothersorsisters 25%chanceofgrandparents Heritabilitycoefficientistheextenttowhichvarationinaparticularcharacteristicwithin groupcanbeattributedtogeneticfactors Heritabilitymeanshowmuchofthevariationinacharacteristicwithinapopulationcan beattributedtogeneticdifferences Eg.Rangeofbodyweights:howmuchofthatrangeisduetogeneticvariances Appliesonlywithingroups Ifacharacteristichashigherconcordanceinpeoplewhoarerelated,thispointstoa geneticcontributionparticularlyiftheylivedindifferentenvironments Inadoptionstudy peopleadoptedinwhichcharacteristicsarecomparedbothbetween thebiologicalparentsandtheadoptiveparents Iftheadopteehasmoresimilaritiestotheadoptedparents,environmentalfactoris moreimportant Iftheadopteehasmoresimilaritieswiththebiologicalparents,thengenticsismore important Eg.Schizophrenia:adoptionparentsonlyhad3%familymemberswiththedisease whilebiologicalparentshad12%,whichshowsthatitisprobablyhereditary TwinStudies Monozygotic(identical)aregeneticallyidentical Dizygotictwins(fraternal)arelikeanyregularbrothersandsisters Identicaltwinshavemanysimilaritiestoeachother Evenwhentheyareraisedindifferentenvironments(separatedearlychildhood) Peoplewithbiologicalfatherswithcriminalrecords,butadoptivefatherwithnocriminal recordhavehighcriminalrecords Peoplewithbiologicalfatherswithlowcriminalrecords,butadoptivefatherswithhigh criminalrecords,hadlowcriminalrecords Ifbothadoptiveandbiologicalfathershadcriminalrecords,thenthechildhasthehighest criminalrecordofall GeneticInfluencesonBehavior - Allofourbehaviorreflecttheinteractionbetweenthegenesandtheenvironment Heredity,Environment,andIntelligence - Supposethatintelligenceistotallydeterminedbygenes Thenthecorrelationbetweenidenticaltwinsshouldbe+1.00 Evidenceshowsthatthisisnotthecase However,themoregenesthatpeoplesharethemoresimilartheirIQwillbe Eg.Biologicalparentsandtheirchildh...
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