The Moon and Venus in even signs with Mars, Mercury, Jupiter and the Lagna in odd signs cause the formation of a twin embryo. The rising sign and the Moon being in even signs and aspected by any male planet cause also twins. Mercury, Mars, Jupiter and the Lagna being in even signs and possessed of strength likewise lead to a twin fetus. There will be a trio of embryos conceived when Mercury in his own Navamsa aspects all planets and the Lagna, or if the Lagna and all the planets occupy Navamsas belonging to dual signs.