Category Archives: Genetics


To what extent is determining gender for sporting competition a scientific question?


 “Gender testing was introduced at the 1968 Olympic games to address concerns that women with ambiguous physiological genders would have an unfair advantage. This has proven to be problematic for a number of reasons. The chromosomal standard is problematic as non-disjunction can lead to situations where an individual might technically be male, but not define herself that way. People with two X and Y can develop hormonally as a female.
The practice of gender testing was discontinued in 1996 in part because of human rights issues including the right to self-expression and the right to identify one’s own gender. Rather than being a scientific question, it is more fairly a social question.”

(BIOLOGY Course Companion, 2014)

The possibility that men might pose as women and be unfair competitors in women’s sports is an outrageous concept to both the athletes and the public. Since the 1930s, media reports have fuelled claims that individuals who once competed as female athletes were in actuality men.

At the Rome Olympic Games in 1960, the International Amateur Athletics Federation (IAAF) began establishing rules for women athlete’s eligibility. Initially, physical examination was used as a method for gender verification, but this plan was widely disliked. This led to sex chromatin testing (buccal smear) being introduced at the Mexico City Olympic Games in 1968.

The principle was that genetic females (46, XX) show a single X-chromatic mass, whereas males (46, XY) do not.

Unfortunately, sex chromatin analysis fell out of use by geneticists after the International Olympic Committee (IOC) began implementing gender verification. The lack of laboratories performing the test heightened the problem of errors in interpretation by inexperienced workers, yielding false-positive and false-negative results.

However, an even greater problem is that there exists phenotypic females with male sex chromatin patterns (e.g. androgen insensitivity, XY gonadal dysgenesis). These individuals have NO athletic advantage as a result of their genetic abnormality and should not be excluded from competition.

Only the chromosomal (genetic) sex is analysed by sex chromatin testing, not the anatomical or psychosocial status.

For all the above reasons sex chromatin testing unfairly excludes many athletes.

These tests fail to address the fundamental injustices of laboratory based gender verification tests. The IAAF considered the issue in 1991 and 1992, and concluded that gender verification testing wasn’t needed. This was thought to be especially true because of the current use of urine testing. Males masquerading as females in these circumstances are extremely unlikely. Screening for gender is no longer undertaken at IAAF competitions.

muscle system
Anatomical differences between female body and male body

table men vs women
men vs women

The testing is humiliating, socially insensitive, and not entirely accurate or effective, causing it to some under scrutiny for those who have acknowledged these facts. It is especially difficult and problematic in the case of people who could be considered intersexual. Genetic differences can allow a person to have a male genetic make-up and female anatomy or body chemistry.

A resolution was passed at the 1996 International Olympic Committee (IOC) World Conference on Women and Health “to discontinue the current process of gender verification during the Olympic Games.” The International Olympic Committee’s board voted to discontinue the practice in June 1999. In individual cases the IOC stills holds on to the right to test on gender.

Newer rules permit transsexual athletes to compete in the Olympics after having completed sex reassignment surgery, being legally recognized as a member of the sex they wish to compete as, and having undergone two years of hormonal therapy (unless they transitioned before puberty).

The International Association of Athletics Federations ceased sex screening for all athletes in 1992, but retains the option of assessing the sex of a participant should suspicions arise. This was invoked most recently in August 2009 with the mandated testing of South African athlete Caster Semenya. This is a sad an infuriating test that was done, insulting Semenya’s talent as an athlete.


Here is a link that explains in full detail the injustice a Spanish hurdler, María José Martínez Patiño, faced when she failed the gender test.

In conclusion, gender verification for sporting competition should be considered only a scientific question if the gender of all the competitors are going to be determined in order for the competition to be fair since anatomically, males are stronger and have more endurance than most females. Nevertheless, if a person identifies themselves as a female and has the body of one then they should be allowed to compete in the female category. Having a genetic disorder that determines you as a male doesn’t justify you to be excluded from the female category since in every other aspect you are one. If this is the reason for why one should be excluded from competing as a female, then every person with a genetic disorder that gives them an advantage should also be disqualified if it is “fairness” that is in question (eg. Eero Mäntyranta, a gold medalist cross-country skier with a genetic disorder that resulted in an increase of up to 50% of his oxygen carrying capacity).

It is unfair that they view the need to do gender testing just based on their physical appearance and that an “underdog” beat out the competition. Sports are extremely competitive, but it should bring unity, not discrimination.

Here is an amazing video that explains the unfairness of using gender verification/testing to prohibit athletes, especially females, for participating in competitions they have rightly trained for.



What criteria can be used to distinguish between correlation and cause & effect 


First, it is important to know what correlation and cause & effect means to be able to distinguish between them

Correlation definition:

Correlation is a mutual relationship or connection between two or more things. Generally it is the degree to which one phenomenon or a random variable is associated with or can be predicted from another.

In statistics, correlation usually refers to the degree to which a linear relationship exists between random variables. Correlation may be positive or negative or inverse:

both variables increase or decrease together.

one variable increases when the other decreases.


 Cause & effect definition:

Cause and effect is the principle of causation. It is making something occur, or is the underlying reason why something happened.
Several factors may be associated with a potential disease causation or outcome, including
predisposing factors
enabling factors
precipitating factors
reinforcing factors
risk factors


Very often, the correlation and cause & effect get mixed up. This is either due to  a misunderstanding or to provide a plausible explanation for a scientific observation. Therefore, it is very important to be able to understand the difference between the two concepts.

Causation involves correlation, this means that if there is a cause and effect then they are correlated. However, correlated events can be caused by a an underlying cause, which means they do not necessarily cause each other, another factor not explicitly mentioned does (a common cause). Just because two events occur together does not imply that one is the cause of the other or that without one  event occurring, the other would not happen.

hidden factor

correlation vs causation comic

 The more solid the correlations, the more likely they are to imply causation.

Eg. the link between smoking and cancer. The correlation between the incidence of cancer and smoking is strong enough that most today consider this to be a cause and effect relationship.

Smoking causes cancer, but cancer does NOT lead to smoking.


Relation of sickle cell anemia and malaria

There is a correlation between high frequencies of the sickle-cell allele in human populations and high rates of infection with Falciparum malaria. Where a correlation exists, it may or may not be due to a casual link.


A causal link is where the Independent Variable has a direct impact on the Dependant Variable.

Sickle cell anemia is when there is a mutation in the genes when the sixth codon is mutated from GAG to GTG. When this allele is transcribed, the mRNA now has GUG as its sixth codon. When this amino acid is coded for, it creates valine instead of glutamic acid. This causes hemoglobin molecules to stick together in tissues with low oxygen concentrations. The hemoglobin molecules distort the red blood cells into a sickle shape.

sickle and red blood cells

The frequency of the sickle-cell allele is correlated with the prevalence of malaria in many parts of the world. Therefore, there IS a causal link. There has clearly been natural selection in favour of the sickle-cell allele in malaria ridden areas, despite it causing severe anemia to red blood cells. Natural selection has led to particular frequencies of the sickle-cell and the normal hemoglobin alleles, to balance the risks of anemia and malaria and this is cause & effect.

In conclusion the criteria used to distinguish between correlation and cause & effect is to differentiate whether both effects that are correlated were caused for a particular and logical reason, without any underlying causes (directly related). And if not, then these effects only show correlation and no causality.

All examples of Correlation vs Cause and Effect are shown in the videos below to visually and aurally help you understand the two.

TEDx Talks – The danger of mixing up causality and correlation:

Ionica Smeets

Khan Academy – Correlation and Causality

Correlation Does NOT Imply Causation