12:10:17 PM Dec 10th 2013
Half identical twins are real, I have seen a couple myself. The misunderstanding comes from the fact that most believe there are only two types of twins, but that is wrong. There are four types. 1) 1 egg, 1 sperm, divides = Identical Twins 2) 2 eggs, 2 sperm = Fraternal twins 3) 2 sperm, 1 egg, fertilizes then divides (rare) = Half identical chimera twins 4) 2 sperm, 1 egg, 1 fertilizable polar body (rare) = Perfect half identical twins (that shares 100% of 50% of their DNA) So this trope isn't purely fictional, of course psychic connection is, but half identical twins do exist.
05:32:16 PM Dec 24th 2011
You know, the article may say that "fraternal twins are no more likely to resemble each other than siblings born years apart," but there is actually such a thing as this in Real Life. It's insanely rare, but it is possible for (I think) something like the cell splitting but two sets of chromosomes...or one egg, two different sperm, somehow.
02:02:47 PM Apr 2nd 2012
The BBC article linked to in this trope talks about a case where a single egg was fertilized by two sperm and then split, both of which are rare occurrences. According to That Other Wiki, there have been cases of semi-identical twins, where the twins have the same genes from their mother but different genes from their father, but how exactly this happens isn't well understood.
01:48:32 AM Jul 31st 2011
12:24:06 PM Mar 14th 2010
I've taken out the Tokamak twins because, as far as siblings go, they really do look very distinct.