Examining each twin’s DNA will reveal whether they are identical or fraternal; fraternals also normally have separate amniotic sacs, as well as separate placentas. Are boy-girl twins always ...

Examining each twin’s DNA will reveal whether they are identical or fraternal; fraternals also normally have separate amniotic sacs, as well as separate placentas. Are boy-girl twins always ...

That's why fraternal twins don't look identical, and can be boy/girl rather than just girl/girl or boy/boy. The majority of twins (70%) are fraternal. Learn your chances of having twins.

Doctors have documented what they say is only the world's second known case of "semi-identical" twins. The boy and the girl, now four ... somewhere between fraternal and identical twins.