To what extent do genetic factors and environmental factors influence the characteristics of identical and fraternal twins?
Intro:
There are two types of twins:
Identical twins - Monozygotic twins: start as one fertilized egg (zygote) and then split into two embryos.
Fraternal twins – Dizygotic twins: two separate eggs fertilized by two separate sperm cells. (genetically identical as two non twin siblings)
(Lykken & Bouchard, 1990)
Identical twins - Monozygotic twins: start as one fertilized egg (zygote) and then split into two embryos.
Fraternal twins – Dizygotic twins: two separate eggs fertilized by two separate sperm cells. (genetically identical as two non twin siblings)
(Lykken & Bouchard, 1990)