23 May 2007

DNA Testing and Identical Twins

It never occurred to me before, but one of the limitations of DNA testing is that it cannot distinguish between identical twins. In the linked article a woman may have had sex with two men who were identical twin brothers on the same night, conceived a child, and is now suing just one of the brothers for child support. As DNA cannot distinguish which of the two is the father, the judge reverted to the traditional eyewitness testimony and felt that the mother was the most reliable witness and therefore took her word that the interviewed brother is the father while he is claiming otherwise.

Similarly, if identical twin brothers were accused of raping someone, or a murderer with an identical twin had left some hair at a crime scene, in neither case could the culprit be positively identified by DNA testing. It's a shame, b/c we do know that eyewitness testimony is quite unreliable.


Galbinus_Caeli said...

So, if she had sex with both men, how would she possibly know which one's sperm performed the fertilization?

zandperl said...

According to the interviewed twin, her story has changed multiple times about whether she actually had sex with both that night, but the story she settled on was that it was only the one twin that she had sex with, the one that she's suing for child support, the one interviewed.

cube said...

I don't know, how about charging each twin half the child support?

BTW it sounds like twins can get away with crime by using the prisoner's dilemma defense & not ratting on eachother.

zandperl said...

Only if there's no other witness. In this instance the mother herself was the primary witness and the judge believed her final statement on which brother was the "culprit".