The Genetics of Psychological Type
By Norbert Grygar
Copyright 2016 Norbert Grygar
by Norbert Grygar 2016
There may be a direct genetic relationship to the eight parts of the Myers-BriggsTM Type Indicator (MBTI) to specific genes and alleles that have yet to be identified.
The specific parts of the MBTI are as follows:
Source of Energy
E – Extraversion – External of the individual such as other living things including persons and physical objects.
I – Introversion – Internal of the individual including the world of thoughts and ideas.
Perception – Taking in New Information
S – Sensing
N – iNtuition
Judging – Arriving at a Decision
T – Thinking – Using logic to come to a conclusion
F – Feeling
Preference for Perception or Judging
J – Judging
P – Perceiving
For those of you that think N or intuition and F or feeling are unscientific as defined by Katherine Briggs and Isabel Briggs Myers, see endnotes 1 and 2 for an alternate explanation of each. The Myers-BriggsTM system works. Therefore, the alternate explanation is not a discrediting of the system, but a way to, perhaps, bring others into acceptance.
In reading the book “Please Understand Me” (Kiersey and Bates 1978) page 25, percentages outlining of the population of Americans that fit into each of the Myers-Briggs Type Indicator (MBTI) sub-parts were given as appears below:
E versus I - 75% of the population is E and 25% I
S versus N - 75% of the population is S and 25% N
T versus F - 50% of the population is F and 50% F
J versus P - 50% of the population is J and 50% P
These numbers looked very familiar.
Further population data contained in the same book about each of the sixteen types generally confirm each of the above percentages.
Now for a quick review of the work of Gregor Mendel involving the inheritance of specific traits involving garden peas (summarized from the book “Blueprints : Solving the Mysteries of Evolution” (Edey and Johanson 1989). Some of the traits studied included the color of the mature peas-yellow versus green, the texture of the mature pea-smooth versus wrinkled, the height of the mature pea plant, tall versus short, as well as some other traits.
The traits found in pea plants mentioned above each existed in pure form in different varieties of pea plants. The individual pea flowers on the same plant contain both male parts, producing pollen or sperm in the pistil part of some flowers, and female parts, ova or eggs found in the stamens of some flowers. The pea plants were most often self-pollinated because a single plant had both male and female parts (homozygous). When each variety was self-pollinated, the trait of the parent plant is the trait of the resulting offspring, yellow or green peas, smooth or wrinkled peas, or tall or short plants. These results will continue as long as self-pollination continues for multiple generations. This is what was meant by pure form. For purposes that follow, this pure form is our first generation.
Mendel began experimenting. By clipping the pistil part of each flower, he could control pollination. He clipped the pistils from the yellow pea variety and pollinated the yellow peas with pollen from the pistils of the green pea. He also clipped the pistils from the green pea variety and pollinated these with pollen from the yellow pea. From this second generation, he harvested the peas to see what resulted. What he got was all yellow peas from each experiment.
Keeping these second generation peas separate, he then planted these peas and allowed each group to self-pollinate. Then he harvested the peas from each group. The resulting third generation peas from each group were not all yellow. The green pea trait reappeared and there were three yellow peas for each one green pea. He called the trait for a yellow pea dominant and trait for the green pea recessive. The proportion of yellow to green peas held the same for succeeding generations. The same pattern occurred when he experimented with smooth versus wrinkled peas with smooth being dominant and wrinkled being recessive.
From Generation two above we see that there are four yellow peas and four smooth peas (each resulting pea carried the dominant yellow or smooth trait) but that the green and wrinkled patterns are still there but not expressed. He then planted the resulting yellow peas and smooth peas. See Generation 3 above for the result of planting the peas from Generation 2. We can see three yellow peas and one recessive green and three smooth peas and one wrinkled pea. As long as the peas from generation three are planted and allowed to self-pollinate, the same ratio of 75% dominate and 25% recessive will continue to appear.
Then Mendel mixed the two dominant and recessive pairs and planted their peas. They produced peas in their second generation and planted those peas. When these peas matured he planted those and in the third generation, he got the following results expressed as ratio of 9 : 3 : 3 : 1 with nine yellow smooth peas, three yellow wrinkled peas, three green smooth peas and one green wrinkled pea.
In the Generation 3 exhibit, the gene pairings present his results. The presentation to the right removes each pair from its box and presents them side by side. For example, note the YS YS pair in the upper left corner box and then again at the top of the first two columns to the right of the display. The yellow colored pea is dominant as is the smooth exterior pea texture. Note that there is at least one dominant Y gene in one or the other columns and there is also at least one dominant S in one or the other of the first two columns. The first two columns contain nine gene pairs representing the number of yellow smooth peas. There is at least one “Y” and one “S” in the either column. The second pair of columns headed by Yw Yw represent the three yellow peas with wrinkled exterior skins. There is at least one “Y” and no “S” in either column. The third pair of columns represent the number of green peas with smooth skins. Here, in either column of this pair, there is no “Y” present but at least one “S”. The final pair of columns contains the one pea that has both a green color and wrinkled skin. There is no dominant “Y” or “S” gene in either column.
In the four pair of columns below the ones discussed immediately above, the columns are reordered to bring together the parts controlling color in first two letters and the second set of two letters likewise for smooth versus wrinkled. This was done for each set of columns. Since no two pairs are alike, no two pair sets will be alike but this pairing makes it easier to see what is happening with a particular gene. The genes of the pea are like humans in that there is a pairing of genes with half from the pollen (or sperm) and half form the ova (or egg).
At the time that Mendel did his research, he was seeking an answer to the question of whether or not traits were blended or passed on to the next generation unchanged. His research backed the point of view that traits did not blend. The scientific community then did not know about chromosomes, genes, or alleles. These all were discovered later. Now we know that chromosomes are like a library of genetic building blocks containing genes that are like individual volumes of specific building instructions. The genes contain alleles that have the actual instructions for building or forming a part of an organism. Mendel’s research reached down and was actually looking at alleles in action.
Now what happens if we look at psychological traits in the same manner as the physical traits described above. The Myers-Briggs type ratios become meaningful. Both of the first two places of the MBTI appear to be occupied by dominant/recessive pairs. The Extroversion trait appears to be dominant and Introversion recessive. And, Sensing appears to be dominant and iNtuition would be recessive. See below. Note that the bottom chart shows both these first two MBTI traits in separate boxes.
The blocked area with the sixteen groups stacked vertically is simply a reordering to show both of the Ei parts together and both of the Sn parts together in a way that makes them easier to work with later. For example, ES ES equals EE SS and this recombination follows for each of the sixteen groups.
Mendel did not work with any trait combinations that the results split evenly.
The third (Feeling/Thinking) F/T pair is something different. The area of concern is that of judgment and I can see only a single gene pair that are both basically alike involved and that there is a switch involving this gene that opts between two competing information streams. From experiments conducted by Dr. Wilder Penfield and described by Dr. Thomas A. Harris in his book, “I’m Okay—You’re Okay” and described in the book’s Preface, we know that memories are recorded in a single stereoscopic steam (that results in a re-living of the event) that is apparently processed by two different areas of the brain. The first is the remembered verbal stream (which includes all that can be recalled and described including for some individuals data thought to be non-verbal) and the second is the all other information but primarily non-verbal stream (including sights and smells, and all other sensual data of which presence is not recorded in our conscious memory or has been lost from our verbal memory). And, somewhere, there is a switch that gives processing preference to the information being retrieved to either the all other including non-verbal stream—the “F” possibility that we cannot remember and vocalize or the verbal stream or the “T” possibility that includes recalled facts with both information sets always available to our central mind internally. Though a judgment gene pair appears to be involved, the important resulting choice is dependant on a switch choosing one area over the other and those results are shown in italic.
The P/J (Perception/Judging) option also does not appear to be a gene or allele but rather the result of an either/or switch. This switch involves a preference for perception or for judging. For this reason, I have shown the P/J option in italic on the two charts below. In each chart below, columns (1) and (2) represent the original results stacked into one column. Column (3) adds the T/F gene option in its two possibilities consisting of T or F with the original information copied twice. Last, the columns (1), (2), and (3) are duplicated twice to show the J and P preferences results by adding column (4).
The next step is to assign the 64 different groups of four pairs into MBTI classes. See below.
According to the above chart, we can also calculate the expected percentage for each type. For INFJ, INTJ, INFJ, and INTP, the expected percentage of the general population is 1/64 or .01565 or 1.565% for each. For ESFJ, ESTJ, ESFP, and ESTP, the expected percentage of the general population is 9/64 or .140625 or 14.0625% for each and for all of the other types, 3/64 or .046875 or 4.6875% for each. See the exhibit below for a comparison of the model and the corresponding numbers found in the book “Please Understand Me” and underneath for the “Do What You Are” by Paul D. Tieger and Barbara Barron-Tieger Ó 1992.
Could the genetics of personality type be so simple? Does the comparison of model percentages to those observed indicate any probabilities that this model is correct?
As a postscript to the above, I finally met with a working geneticist and had him review the above article. Basically, he said that he would want to see some basic genetic research involving observation and testing of human subjects. For example, as yellow smooth peas generally produce yellow smooth offspring, do pairs of ES parents generally produce ES children in the same manner? And, even though both T and F split evenly, as does P and J, is it more likely if the parents share a common letter, then their child or children will share the same letter or characteristic? There are statistical tests that can be performed with each of the MBTI types involving multiple generations with persons of known MBTI types that can lead to needed answers. Only after this type of research is completed and with the data suggesting genes or alleles being involved, would he suggest going forward to look for such actual components. None of the above, at this time, negates or denies the premises of there being genes/alleles directly involved in psychological type as outlined.
1. “N” or iNtuition was defined as “indirect perception by way of the unconscious, incorporating ideas or associations that the unconscious tacks on coming from the outside.” (Gifts Differing, Briggs Myers 1980 page 2). All perception begins with the senses. As new information is being received by the “intuitive” individual, their mind or brain immediately starts looking for a place to store and link the information to related data and these individuals are indirectly (subconsciously) sensitive to that search. Sometimes, a question or thought comes into the conscious that would help the brain in its storage and linkage process. The questions and observations are not from without the person but from within. This process, then, I would describe as “Sensing Plus” and I have internalized the “N” to be “seNsing Plus”.
2. “F” or Feeling, as a judging process, was defined as “ The other (way of judging) is by feeling, that is by appreciation-equally reasonable in its fashion-bestowing things a personal, subjective value.” The previous sentence, in same book, concerning thinking indicates that it is “a logical process, aimed at an impersonal finding.” (Gifts Differing, Briggs Myers 1980 page 3) I would suggest that all judging processes for both “T” and “F” individuals begin with the same thought streams of verbal and non-verbal information available and given no other information but facts devoid of any sensual or prior contact side information, both would reach the same conclusion. However, in the world of people and things, in many given situations, there is much additional information available from the realms of non-verbal information including verbal presentation (inflection, cadence, tone, etc.), body language and prior experience. When this additional information is used, all or most of the decision process is not “remembered”. I personally describe “Feeling” as “Thinking Plus”. To myself, I see a “T” with a plus (+) superimposed on top of the “T” and then the two horizontal lines to the left of the vertical line removed. Then, I see an “F”.
“Blueprints : Solving the Mysteries of Evolution” by Maitland A. Edey and Donald C. Johanson ©1989 Chapter 5 pages 105-122
“Please Understand Me” by David Kiersey and Marilyn Bates ©1978
“Gifts Differing” by Isabel Briggs Myers with Peter B. Myers © 1980