A Genetically Transmitted, Benign Habit: A Case Report and Review

Main Article Content

A. S. V. Prasad


Habits are defined as acquired, repetitive, involuntary and body focused, stereotyped motor acts. Tics have the same attributes, but are characterised by muscle spasm additionally. So far, the emphasis in the literature is that the habits are acquired. There is no reference in the literature as to the habits being transmitted genetically. Whereas in the case of tics, some like, Tourette Syndrome (TS), are accepted to have genetic basis Habits are harmless. But some are self - destructive Out of the group of the four destructive habits, like trichotillomania (TTM), bruxism, scabiomania or skin pulling (SP) and onychophagia, TTM, along with chronic persistent motor tics, persistent vocal tics and combined motor and vocal tics like TS, are grouped together, as habit disorders by the American Psychiatry Association (APA) Statistical Manual of Mental Disorders classification, 4th edition (DMS 4). Virginia Commission recommends inclusion of SP also under habit disorders. Other authors include all the four destructive habits under the habit disorders. It is also accepted that habits are related to behavioural patterns and that the behavioural patterns are genetically determined. Thus an indirect link is established between the habits and heredity, through behaviours. The author presents in this article, a benign, ‘nose rubbing habit’ being transmitted through 6 generations in a family tree. Unique to the pattern of inheritance, 100 % desendents in some generations (generations 1,2 and 3) with involvement of both males and females, without any skip generations, is seen .Very early onset is recorded at the age as low as 2 years and as high as 6 years belonging to the in the 6th generation. This is the first of it’s kind reported in literature that a benign habit is shown to run in a family, across 6 generations. This is contrary to the popular belief, that habits are always acquired. If it is so, what is it that irrefutably transmitted through 6 generations in this case? Mitochondrial gene (mtDNA) transmission, involving recombinant maternal and paternal mtDNA, is suggested, by inference and after eliminating the other Mendalean and non Mendalean types of inheritance. Of course, the main intended focus of the article is to highlight the transmission of a habit- trait (?) genetically. As a possible explanation of this observed phenomena only, the tentative inheritance pattern is suggested. The matter is open for discussion by the concerned fraternity.

Habits, tics, habit disorders, mitochondrial inheritance, tourette syndrome.

Article Details

How to Cite
S. V. Prasad, A. (2020). A Genetically Transmitted, Benign Habit: A Case Report and Review. Asian Journal of Case Reports in Medicine and Health, 2(4), 1-9. Retrieved from https://www.journalajcrmh.com/index.php/AJCRMH/article/view/30115
Case Report


Bishal Khatiwada. Behavioral genetics – How are genes and behavior linked? Exposure Biotech; 2019

Matthew D. Egbert, Xabier E. Barandiaran. Modeling habits as self-sustaining patterns of sensorimotor behavior. Front. Hum. Neuro Sci.; 2014.

Available:https:courses.lumenlearning.com›...Genetics and Behavior | Boundless Psychology- Lumen Learnin [Melissa Darcey. "10 Habits, Traits and Preferences You Didn’ti Know Your Genes Determined" Pathways genomics; 2017.

Tim Kurz, Benjamin Gardner Bas Verplanken Charles Abraham. Habitual behaviors or patterns of practice? Explaining and changing repetitive climate-relevant actions" Wily online library; 2014.

Saul McLeod Nature vs nurture in Simply Psychology.
Available:http://www 2007

Breed M, Sanchez L. Both environment and genetic makeup influence behavior. Nature Education Knowledge. 2010;3(10): 68.

Griffiths, Paul. The distinction between innate and acquired characteristics. The Stanford Encyclopedia of Philosophy (Spring 2017 Edition), Edward N. Zalta (ed.), Robert Plomin. "Genetics and behivour. Behaviour genetics. 8rains. com. (Behv gen study).

McGue M, et al. Genetic and environ-mental influences on human behavioral differences. Annu Rev Neurosci; 1998.

Proud, Virginia, Roberts, Helen. Medical genetics: Multifactorial inheritance. Children’s Hospital of the King & Aposs Daughters; 2005.
[Retrieved 6 January 2007]

Matthews SG, Phillips DI. Trans-generational inheritance of stress pathology. Review. Experimental Neuro-logy. 2012;233 (1):95–101.

Birky C. William. The inheritance of genes in mitochondria and chloroplasts: Laws, mechanisms, and models. Annual Review of Genetics. 2001;35(1):125–148.

Giles RE, Blanc H, Cann HM, Wallace DC. Maternal inheritance of human mitochondrial DNA. Proc. Natl. Acad. Sci. U.S.A. 1980;77(11):6715–9.

Satoh M, et al. Organization of multiple nucleoids and DNA molecules in mitocho-ndria of a human cell. Exp Cell Res; 1991.

Schwartz M, Vissing J. Paternal inheritance of mitochondrial DNA. N. Engl. J. Med. 2002;347(8):576–80

DR Johns. Paternal transmission of mitochondrial DNA is (fortunately) rare. – NCBI Ann Neurol. 2003;54(4):422.

TG McWilliams. Mitochondrial DNA can be inherited from fathers, not just mothers. – NCBI. Nature. 2019;565(7739):296-297.

HJ, Kong QP, Parson W, Salas A. More evidence for non-maternal inheritance of mitochondrial DNA? American Journal of Medical Genetics. 2005;42(12):957–60.

Luo S. Biparental Inheritance of Mitochondrial DNA in Humans PNAS. 2018;115(51):13039-13044.

Kraytsberg Y, et al. Science. HJ, Kong QP, Parson W, Salas A. More evidence for non-maternal inheritance of mitochondrial DNA? American Journal of Medical Genetics. 2005;42(12):957–60.
DOI: 10.1136/jmg.2005.033589.

Dnae D, Ladoukakis A. Eyre-Walker. Evolutionary genetics: Direct evidence of recombination in human mitochondrial. Heredity. 2004;93:321.

Strauss E. Human genetics. mtDNA shows signs of paternal influence. è. 1999; 286(5449):2436a–2436.