Inherited Characteristics In Fingerprints:
(or Theory of Relativity)

(This story originally appeared in volume 4 issue 5 of the �The Print� in September 1991.)

Kern County Sheriff Dept.

The question of heredity in fingerprints is often asked in basic fingerprint training classes.  It's a legitimate question that often doesn't receive a satisfactory answer.  The students are told that occasional similarities extend only to pattern types.  This answer is misleading in that it infers no possibility of complex similarities in the ridge structure.  

My first experience with striking similarity of two prints came about while attempting to verify the identity of a prisoner booked under his brother's name.  The thumb prints, at first glance, were so much alike that I started to initial the identification.  Closer examination saved me the embarrassment of a bum ident.  I chalked the whole thing up to my imagination.  

Over the years, while working in Prisoner Identification, I ran across other brothers and Juniors and Seniors with more than co--incidental similarities but kept my mouth shut fearing ridicule from my peers.  

Finally, years later and now a Latent Print Examiner, I was confronted with a comparison in which the latent and known print were so much alike as to be incredible.  I knew these people were related.  Feeling somewhat foolish and a little blasphemous I called the officer who had requested the comparison and, with the telephone mouthpiece shielded to prevent anyone in my office from overhearing, inquired as to the possibility of a brother of the offered subject being the culprit.  He gave me a name and I was rewarded with a positive comparison and the subsequent successful prosecution of that brother.  Since that time I have made two more cases because of striking similarities.  

When my Granddaughter's Third Grade class decided upon fingerprints as a science project, I took advantage of the occasion to obtain and compare the prints of entire families.  It was my hope to find one or two good examples of hereditary characteristics to back up my beliefs.  What I found exceeded my expectations.  In all family groups, I was able to locate common ridge characteristics in addition to the overall sameness of pattern shapes and sizes.  

I am not suggesting that 'fingerprints' are strictly hereditary, only that peculiarities in ridge structure recur with the same frequency and to the same degree as those other more obvious family traits such as hairlines, noses, ears and eyes.  

If you are comparing an unidentified print with those of a known person and the similarity is striking, you could be looking at the print of a close relative of that person.  Don't pass up an opportunity to find out.

(Editor--� While this information is related in other studies of friction skin.  Tom's straightforward fashion points out what can be a very useful investigative lead.  Either for the examiner to look for exemplars of a relative or provide the investigator with a request to provide exemplars of siblings etc.)

This article was originally published in �THE PRINT�
Volume 4(5), September 1991 and then again in
Volume 13(1), January/February 1997, pp 1-2
and has been obtained from the online library provided by the

Southern California Association of Fingerprint Officers