The Twinning Process

 Many people ask me whether or not the boys are identical.  The answer is, we don't know.  When I tell people we don't know they look at me like I'm stupid for not knowing.  Let me show you how the twinning process works.

Most of us know there are fraternal twins and identical twins.  We know fraternal twins are the result of two eggs and two sperm. (Babies share 50% DNA).  99.99999% of the time boy/girl twins are fraternal.  So don't ask someone with boy/girl twins if they're identical.  Fraternal twins are ALWAYS dichorionic/diamniotic. This means they each have their own amniotic sacs and each have their own chorionic sacs, along with their own placentas. (However, placentas can fuse during pregnancy.)

And we also know that identical twins results from one egg splitting.  When it splits determines a lot.

-If the egg splits after 13 days of fertilization it will result in monochorionic/monoamniotic. Sharing one sac and conjoined twins may result.

-If the eggs splits between 8 and 13 days after fertilization it will result in monochorionic/monoamniotic. Sharing one sac and will run the risk of the cord tangling.

-If the egg splits between 3 and 8 days after fertilization it will result in monochorionic/diamniotic.  Rach having their own amniotic sacs but sharing one chorion and sharing one placenta.


-If the egg splits 3-4 days after fertilization it will result in dichorionic/diamniotic.  Each in their own sacs and have their own placenta (however, the placenta can fuse)

You see the last possibility is the same as fraternal twins.  If you have dichorionic/diamniotic twins the doctors do not know whether it resulted from two eggs or one egg splitting, therefore the only way to be 100% sure that they are fraternal or identical is to do a DNA test. (Unless they are boy/girl twins, then you know they are fraternal)

I was told early on in my pregnancy that the boys were di/di twins...My placenta did come out as one. (I'm assuming it fused)  The only way to know if they are identical is a DNA test.  Now if they would have recorded their blood type which they didn't it could help.  If they do not have the same blood type, they are not identical, however they can still have the same blood type and be fraternal, that is why the DNA test is needed.

Hope this all makes sense.