Twin Sisters

This results in a set of twins with identical genes from the mother's side, but different genes from the father's side. Cells in each fetus carry genes from either sperm, resulting in chimeras. This form had been speculated until only recently being recorded in western medicine.
Animal twins
Twins are common in many animal species, such as cats, sheep, ferrets and deer. The incidence of twinning among cattle is about 1–4%, and research is under way to improve the odds of twinning, which can be more profitable for the breeder if complications can be sidestepped or managed. The nine-banded armadillo (Dasypus novemcinctus) has identical twins (usually four babies) as its regular reproduction and not as exceptional cases.