PSYC 2500 Lecture Notes - Lecture 3: Birth Order, Human Chorionic Gonadotropin, Egg Cell
29 Jan 2018
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Document Summary
Monozygotic (identical) twins come from a single fertilized egg that splits after conception: identical genetically, differences are a result of their environment. Dizygotic (fraternal) twins come from two separate eggs fertilized by two sperm cells: no more genetically similar than siblings, similarities are a result of their environment. Twin studies compare identical and fraternal twins. If identical twins are more alike than fraternal twins, heredity is likely the influence: weakness twins may be treated more alike. Adoption studies: provide information about heredity, adopted children co(cid:373)pared to , biological and adoptive parents. Behavioural consequences of genetic instruction depend on the environment in which those instructions develop. Reaction range: same genotype can produce a range of phenotype in reaction to the environment, ex. Pku genotype: those who eat a normal diet will become developmentally delayed, but those who eat a special diet will have normal intelligence: certain individuals can handle higher or lower levels of phenylalanine.
