The science of homosexuality

21st January 2010

The temptation is too great, I cannot resist  any longer, as much I have tried not to sully my hands in this very torrid affair, I feel I have to say something, well at least something scientific – as I can get away without possibly saying anything too controversial – on homosexuality. The engagement of the two Malawian men Tiwonge Chimbalanga (20) and Steven Monjeza (26) has caused such an uproar around the world particularly after the Malawi government arrested and charged the two with gross indecency. Gross indecency, depending on where you look,  is a  sexual act that does not result in actual intercourse e.g. anal sex, masturbation, indecent physical contact, or even indecent behaviour without any physical contact.  British Law which is supposed to be the basis of Malawian Law seems more up to date on this as their constitution defines it as “anal sexual intercourse with another man without consent”.  All this begs the question will the court be able to prove that these two gentlemen had “sexual relations” (a phrase borrowed from yours truly “BC”). The photographs show Chimbalanga to be rather effeminate – wearing female clothes and  investigations by a Malawi Daily Times reporter  revealed that Tiwonge would perform womanly duties around the house and would even apparently menstruate.  If Tiwonge believes himself to be woman is that homosexuality? Anyway….. mine is not an argument on the law but of science. So I decided to do some digging and I found some interesting things that I would like to share with you.

Did you know that it was only in 1973 that the American Psychiatric Association declassified homosexuality as a mental disorder?  Or that there is a scientific journal on homosexuality? I kid you not, the Journal of Homosexuality has been publishing scientific studies in this area as far back as 1976 but it is not the only journal that publishes sexual orientation studies.  I came across thousands of studies e.g. One 2004 study found and I quote  “ homosexuals have more maternal than paternal male homosexual relatives, that homosexual males are more often later-born than first-born and that they have more older brothers than older sisters.” In other words homosexuals have more homosexual relatives from their motherside and that they tend to be a middle born with a lot more older brothers than older sisters(1).  Another study  published in 1999 in the Journal of Personality and Social Psychology titled “Lesbian erotic role identification: behavioral, morphological, and hormonal correlates” by scientists at the University of Texas looked at butch and femme classifications of lesbianism (2). A 2002 study at the University of Berkeley investigated the “Differences in finger length ratios between self-identified “butch” and “femme” lesbians”  (3). This study was based on the controversial  theory that the ratio of index and ring finger lengths is a marker of how much androgen (collective term for masculinising hormones) a person was exposed to,  with heterosexual women having a higher finger ratio followed by homosexual men and then heterosexual men.  There were a number of papers that even my biochemist brain could not understand  like “Gene- and environment-dependent neuroendocrine etiogenesis of homosexuality and transsexualism” (4).

Is homosexuality genetic – is it a learned behavior or are people born this way – is a question I  can hear you asking. It is a difficult one to answer as there is are ongoing contentious scientific debates on this topic but I think it is safe for me to say that human sexual orientation is influenced by  the interaction of several biological, cognitive, cultural, and environmental factors that lead to multiple types of heterosexuals, bisexuals, and homosexuals.  So Ladies and Gentlemen in conclusion, there is a lot of ongoing research in this area so let us judge not, what we do not know…..


  1. Camperio-Ciani A, Corna F, Capiluppi C. Evidence for maternally inherited factors favouring male homosexuality and promoting female fecundity. Proc Biol Sci. 2004 Nov 7;271(1554):2217-21.
  2. Singh D, Vidaurri M, Zambarano RJ, Dabbs JM Jr. Lesbian erotic role identification: behavioral, morphological, and hormonal correlates. J Pers Soc Psychol. 1999 Jun;76(6):1035-49.
  3. Brown WM, Finn CJ, Cooke BM, Breedlove SM. Differences in finger length ratios between self-identified “butch” and “femme” lesbians. Arch Sex Behav. 2002 Feb;31(1):123-7.
  4. Dörner G, Poppe I, Stahl F, Kölzsch J, Uebelhack R. Gene- and environment-dependent neuroendocrine etiogenesis of homosexuality and transsexualism. Exp Clin Endocrinol. 1991;98(2):141-50.

5 thoughts on “The science of homosexuality

  1. Keep digging! The factors that influence homosexuality are therefore the same factors that influence other more acceptable forms of sexual behavior. What is of interest is to me regarding the malawi case is the response society has shown ‘deviants’ who in essence harm noone and as adults should be free to make choices on their inclinations (e.g missionary or 69 as other couples do) as long as no minors are involved just as in ‘normal’ sexual relations. I recall a reponse from the sunday times agony aunt some years ago to a wwriter who was disturbbed that his female lover wished to engage is oral sex; the agony aunt advised against it as ‘immoral’. We therefore dealing, in malawi, with a narrow but probably closeted highly sexual but repressed society- check the daily sex scandals. It is the physiological effects of anal sex – which some hetero couples also enjoy- that point to the fact that the anal act is not what the body was built for. Could u scientifically elaborate on these?

  2. I have been trying to understand all this but am failing. Maybe my brain is too small. I am very interested to know if this can be an inborn condition (am trying hard not to call it a disorder)? Someone confessed to me that it is rampant in boarding schools especially same sex boarding schools. keep researching on our behalf so that as they say “the truth shall set us free”.

  3. A few have asked me what am I trying to say….well there is a lot of research going on homosexuality and i think we should not judge what we don’t know…..

  4. The science may not be conclusive on whether homosexuality is genetic or learned, but there is A LOT of evidence to show it is a natural and common behaviour in the rest of the animal kingdom. A BBC news article on an art exhibition states, “…homosexuality has been observed among 1,500 species, and that in 500 of those it is well documented.” Researchers are even now looking at ways in which homosexuality may have evolved and if it may even be beneficial for some animals.
    Many species have also been recorded in other ‘grossly indecent’ acts, such as having group sex, oral sex, and masturbating.

    I’m not saying we should set our moral compass by animals (after all, bed bugs have institutionalized stab rapes), but it does suggest that homosexuality isn’t some freakish deviant act- it’s just nature.

    BBC News:
    Nathan W. Baileya, and Marlene Zuka (2009) Same-sex sexual behavior and evolution. Trends in Ecology & Evolution 2 (8): 439-446
    Jonathan Balcombe (2009) Animal pleasure and its moral significance. Applied Animal Behaviour Science 118 (3-4): 208-216
    Bedbugs and stab rape:

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