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View Full Version : Why don't identical twins share fingerprints?


SenorBeef
10-26-2001, 11:03 PM
Is it because there's some environmental factor that affects finger tip development?

Smeghead
10-27-2001, 12:28 AM
Mainly it's because it's a largely random process.

There's more to life than DNA.

MEBuckner
10-27-2001, 12:45 AM
From Do identical twins have different fingerprints? (http://www.straightdope.com/classics/a980821.html)
Twin fingerprints are much beloved by scientists, who see them as a classic arena for the old nature-versus-nurture debate: What made you what you are today, your genes or your environment? Twin fingerprints clearly show that it's a little of both. If you compare palm prints and fingerprints of the Dionne quintuplets (born in 1934, they were the first quints of which all five survived), you find that the broad-brush pattern of lines, whorls, loops, etc., as well as what researchers call "ridge count," were quite similar for the whole crew. Nonetheless each kid had unique prints due to differences in detail. "There is as yet no evidence that the arrangement of the minutiae (ending ridges, bifurcating ridges, etc.) is in any way genetically influenced," writes fingerprint expert James Cowger. Presumably these minor but crucial differences arise from random local events during fetal development, the same kind of thing that makes each snowflake unique.
(emphasis added)

Neurodoc
10-28-2001, 12:50 AM
Were they identical? I don't know. But it seems strange that > twins would be identical...more likely fraternal.

In any case identical twins should have identical DNA profiles. Since no two humans have ever been found to share fingerprints, does this mean that in forensics good old fashioned fingerprint matching is more certain than the highly touted DNA technology?

MEBuckner
10-28-2001, 01:03 AM
According to the Encyclopedia Britannica (http://www.britannica.com)The University of Toronto conducted biological, psychological, and dental studies of the quintuplets. The biological study established that the set originated from one fertilized egg. The Dionne quintuplets arose through repeated twinning of the early single embryo; therefore, six embryos were produced, and the five infants surviving birth inherited the same genetic material.
And yes, fingerprints would be of more use than DNA evidence in establishing that it was really O.J.'s Long-Lost Evil Twin that did it.

DPWhite
10-28-2001, 01:30 AM
Fingerprinting is not a science and there is growing controversy in the courts (still rather small) about what constitutes a match. Whether a crime scene latent and/or partial fingerprint is a match is usually a judgment call. Some jurisdictions require as little as 8 points of similarity. In the UK IIRC it is about 15. That is a huge difference. And virtually anyone allowed to testify on whether a fingerprint is a match has been trained by police.