Will You Get Divorced If You’re an Only Child?

Researchers have often thought that personality development is influenced by a child’s birth order. Research has supported these hypotheses, and the influence of birth order is so strong that the lifestyle of two youngest children in two different families is more similar than that of a middle and youngest child in the same family (Romeo 1994).

Birth order often defines one’s role in the family. Dr. Kevin Leman, author of “The New Birth Order Book: Why you are the way you are,” believes birth order is the science of understanding your place in the family line and affects one’s life in countless ways (1998).

According to Michalski and Shackelford (2002), the oldest children hold positions of parental favor and dominance in relation to younger children and the younger children show different characteristics to secure parental investment. First-born children are often thought of as perfectionists, scholarly, high achievers, leaders and reliable. A lot of oldest children have the undivided attention of the parents before other siblings are born. These kids most often interact with adults for the first part of their lives. First borns are often given responsibilities for younger siblings from the parents as they age, which boosts characteristics of leadership and dominance (Romeo 1994). In research, Pines finds that first borns score higher on self-esteem tests when compared with other children (cited in Romeo, 1994).

Middle children are often “different” to stick out in the family since they are neither the oldest and leading the way, or the last, the baby of the family who seems to get a lot of attention. Middle kids are usually described as being a compromiser, diplomatic, loyal to their peers, and having many friends. Middle children develop humor that amuses older generations as well as younger kids and often can become exhibitionistic to gain attention (Romeo, 1994).

Youngest kids seem to be outgoing, charming, and blaming others. They love surprises, seeking attention and are people persons. The babies of the family might shy away from tasks for fear of failure and are often reminded of their shortcomings from their older siblings (Romeo, 1994). Youngest children can also develop personality traits similar to an only child since youngest children tend to come several years after the oldest kids.

After conducting his experiment, of birth order and personality with a N of 1022 families, Paulhus believes that the differences in personality, yet the similar traits to other kids with the same birth order is because of the siblings competition for uniqueness and for a niche in the family (1999).

In an experiment done by Stewart, Stewart and Campbell (2001), with 422 participants and a mean age of 19.2 years, being a first born predicted scores on the first child score of the Psychological Birth Order Inventory. Psychological middle scores were predicted by general family dysfunction and youngest scale scores were predicted by the need for acknowledgment and attention.

A study was done on the influences of the family environment on personality traits. Testing 150 children, thirteen behavioral characteristics identified three personality traits: extraversion, maturity, and intellect (Nakao 2000). Eight percent of variance in extraversion, ten percent of variance in intellect and fourteen percent variability in maturity was due to family environment (Nakao 2000).

Since research supports that birth order seems to shape one’s personality, and some people seem to be more compatible with certain types of people, does birth order have an effect on compatibility in relationships? Dr. Leman thinks so. Many people expect to get married, stay with that partner until death, and enjoy a relationship that is secure and fills their needs. Yet, it is a fact that nearly 50% of marriages today end in divorce. Statistics show that approximately 20 million divorced people live in the USA, and the median duration of any given marriage is approximately 7.2 years (Leman, 1998).

Few people consider the power that their birth order has played in developing their own thoughts, beliefs, quirks and their overall personality. Even fewer people probably think about how it has affected their prospective spouse’s personality. Do they ever stop to consider how the two personalities might make life living together under one roof? This makes sense. If the baby of the family is known to be an attention seeker, and two youngest born children marry, they will both be seeking attention, and not giving nearly as much attention to the other person. If two eldest born kids marry, and they are both leaders, who leads? Wouldn’t it make sense to marry someone who complimented one’s personality?

In this study I will test the above proposals of birth order affecting personality. I found few studies that examine birth order and compatibility, however, it is reasonable to speculate that compatibility is affected by one’s birth order, so I will also be testing this. If research supports that birth order affects personality, and it is assumed that two people with only certain personalities are compatible in a long-term relationship, birth order probably affects whom we are compatible with.

Since birth order, personality and who someone dates or for how long cannot be manipulated by the experimenter, this design is considered to be a correlational study.

Two hundred heterosexual male and female participants, 21 years old or older, will be sampled. This breaks down to one hundred couples. Couples may come together, or two persons who have dated previously can participate. The couples must have been dating for at least eight months prior to breaking up, or are still dating. It is assumed that one’s personality and traits are defined and pretty solid by the time they reach this age and are in college or a field of work.

Ethnicity, religion, social status or background will not play a factor in participants’ eligibility to participate in this study since we want the study to be as diverse and representative as possible.

Each person will be given two tests and a questionnaire to fill out. The first test will be a personality test. This test will give a series of questions assessing the personality of the participant. It will include statements about personality with true or false answers; some statements will have multiple-choice answers to choose from as well.

Next, each person will be given a relationship test intended to evaluate a variety of aspects of interaction in a relationship. Some areas of questions include one’s feelings for the partner, communication, support and security, responsibilities, conflict, social life, jealousy, hobbies and interests of the couple spent together, freedom and, finances. This will also be a multiple choice and true and false format.

The questionnaire is a simple form to fill out about the participants’ family including questions about birth order, number of brothers or sisters and other background information such as age, gender, ethnicity, religion, or social status.

Each participant will be given the two tests and questionnaire to answer. Each person will finish these tests independently from their partner and are told not to communicate with their partner while taking the tests as to not have them influence each other’s answers. Participants will be instructed to read every statement thoroughly and mark which answer they feel best represents what they would do. If there are questions or statements that do not apply to a participant, they will be instructed to choose an answer that they would most likely choose if they were ever found in that situation. The participants may take as much time as they need to finish these tests. Every participant is also encouraged to write any other details about their relationship that they think are critical for the researchers to know.

When all the testing is done, the participants’ personality types will be assessed from the personality tests. After this is done, it will be checked to see if these personalities fit with their birth order in the family.

From the relationship test, it will be determined how happy the participants said they were, look at their partner’s relationship test and see how happy they are with the relationship. After doing this, we will see if there is any kind of correlation between birth order and compatibility or if there is any kind of pattern as to what birth order and/or personality type dates or marries a certain type of personality. Then, it will be noted how compatible they seem to be.


Leman, K. (1998). The new birth order book: why you are the way you are. New York: Flemming H. Revell Co.

Michalski, R. L., Shackelford, T. K. (2002). An attempted replication of the relationships between birth order and personality. Journal of Research in Personality, 36, 182-188.

Michalski, R. L., Shackelford, T. K. (2001). Methodology, birth order, intelligence and personality. American Psychologist, 56, 520-521.

Nakao, K., Takaishi, J., Tatsuta, K., Katayama, H., Iwase, M., Yorifuji, K., & Takeda, M. (2000). The influences of family environment on personality traits. Psychiatry and Clinical Neurosciences, 54, 91-95.

Nyman, L. (2001). Identification of birth order personality attributes. Journal of Psychology, 129, 51-59.

Paulhus, D. L., Trapnell, P. D. & Chen, D. (1999). Birth order effects on personality and achievement within families. Psychological Science, 10, 482-488.

Romeo, F. (1994). A child’s birth order: Educational implications. Journal of Instructional Psychology, 21, 155.

Stewart, A. E., Stewart, E. A., & Campbell, L. (2001). The relationship of psychological birth order to the family atmosphere and to personality. Journal of Individual Psychology, 57, 363-387.

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