research involving twins. The reason for this research is generally to evaluate the relative contributions of environment and genetics to some attribute. Particularly, frequently consists of comparing the traits of fraternal and identical twins and comparing twins of both kinds who have been raised together or apart. 1) Identical twins raised apart. Here the genotypes are the same, but since there's no shared environment, disparity of intellect must be an outcome of the distinct environments. 2) Comparisons of identical twins raised together and fraternal twins raised together. Here, one can presume that each twin set shares the same surroundings, but while the identical twins have all of the same genes, the fraternal twins have only half of the same genes.