Polygenic and Multifactorial Traits

 Polygenic traits reflect the activity of more than one gene, and multifactorial traits are also influenced by the environment. 

Twins

Because twins have identical or similar genes, it is easy to determine what traits are influenced by the environment.   

DZ Twins

  • Dizygotic  twins (nonidentical)
  • share same environment  & 50% of their genes

MZ Twins

  • Monozygotic twins (identical)
  • same genes & environment

 Schizophrenia

  • Symptoms: hallucinations, delusions, thought disorders, movement disorders
  • Environmental factors: prenatal exposure to viruses & malnutrition before birth
 

Multifactorial Traits

  • Height: dozens of genes affect height, but an idividual's diet also influences their height
  • Skin Color: depends on the phenotypes inherited from parents and amount of exposure to sunlight
  • Body Weight: genes control leptin (suppresses appeitite and increases metabolic rate) and other related proteins, also depends on diet and exercise    

 

 

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