Is it possible to have fraternal conjoined twins? My (limited) knowledge of how twins are created led me to wonder about this. If the twins were created from seperate eggs, how could they have become conjoined?
Identical Twins come from one egg that divides completely and forms two individuals. For all purposes their DNA is identical.
Conjoined twins fail to divide completely.
In order to be conjoined and fraternal they would have to come from two eggs fertilized and then fused together.
to come from two eggs fertilized and then fused together
… which happens; you get a chimera. However, as far as I know chimeras generally involve two embyros fusing completely at a very early stage of development. I don’t know if it can happen late enough to create conjoined individuals.
Fraternal twins develop in separate amniotic sacs. They don’t have any chance of touching enough to grow together.
Cite (I don’t like this page’s use of “bi-amniotic” instead of “diamniotic”, but it gets the point across)
Identical twins can be diamniotic, too. But if they’re monoamniotic, then they have a chance of being conjoined. That’s the only way it can happen.