Intelligence and Birth Order: Are They Connected?

Abstract
There have been many examinations of birth order and the effect it has on a person’s intelligence. Some researchers feel that first-born children have higher IQ’s than that of their younger siblings. It has been said that first-born children are natural leaders. Siblings of first-born children perceive them to be academically smarter. Eldest children are known to perform higher on standardize testing than younger children in the family. Other researchers have stated that family size/home life, age of mother and circumstances around the birth of each individual child determines where they are intellectually. Researchers need to look at every aspect of the child’s life before they decide which child is smarter. Intelligence and Birth Order: Are They Connected? Birth order is where a person ranks in regards to age among their siblings, from oldest to youngest and vice-versa. There is much debate on the relationship between a person birth order and how intelligent we are. Many studies have been done to determine if there is a link to the firstborn having a higher IQ in general compared to their siblings. Some people would agree that birth order has a profound influence over intelligence; however, others are in opposition to this. The opposition feels that birth order has no effect when it comes to intelligence. Does birth order cause children to have lower or higher intellect or is this caused by factors within the home? There have been many studies over the last century to explore the effects of birth order. Researchers have said that there is significant evidence in regards to birth order and a person’s intelligence. There have been many studies on the subject of birth order; including the research done by Lillian Belmont and Francis Marolla in 1973. This particular study was said to show a negative association between intelligence performance and birth order. Their study resulted in individuals with higher birth order doing better on standardized testing than individuals with lower birth order (Belmont & Marolla, 1973). Many psychologist and sociologist have done their best to explain why they think birth order is associated with intelligence through various models. The studies having the biggest impact also focused on how children interact with their family and intellectual favorable conditions (Kristensen & Bjerkedal, 2001). In 1996 researchers from Ohio State University at Mansfield and the University of British Columbia did studies on four separate groups of people in regards to birth order. This study asked participants to write down the birth order of their brothers and sisters, including themselves. They were asked to point out the sibling who had better overall academic achievement. Each study was done under different circumstances, like in the classroom or as a take home assignment. The outcomes were similar to other studies on this subject. “Our finding that first-born’s are perceived as more intellectually achieving than later-born siblings is consistent with previous work” (Paulhus, Trapnell, & Chin, 1999, p. 487, p. 2). The findings from a study done in 2007 explained that, “Firstborns are generally smarter than any siblings who come along later, enjoying on average a three-point IQ advantage over the next eldest - probably a result of the intellectual boost that comes from mentoring younger siblings and helping them in day-to-day tasks” (Kluger, 2007, pp. 1, 6). According to Kluger 2007, firstborns thrive and end up leading or taking charge of corporations. “Poll takers reported that 43% of the people who occupy the big chair in boardrooms are firstborns, 33% are middle-borns and 23% are last-borns” (Kluger 2007, pp. 2, 9). Eldest born children are usually doctors and other important fields helpful to people. “Just 2.3 IQ points can correlate to a 15-point difference in SAT scores, which makes an even bigger difference when you're an Ivy League applicant with a 690 verbal score going head to head against someone with a 705” (Kluger, 2007, p 6). Many factors are behind the reasoning birth order effects intelligence. “There is no genetic component to birth order; there may be biological differences by birth order resulting from differing experiences in utero” (Black, Devereux & Salvanes, 2007, pp. 11, 2) The expected mother’s quality of pre-natal care and their behavior may be different during each pregnancy. A study was done that showed a direct connection between birth weight, length and the size of the child’s head with their intelligence. In this study these birth characteristics positively correlated with birth order, which showed that later-born children do just as well (Black, Devereux & Salvanes, 2007). The idea is that the order in which we are born is no longer significant due to recent studies. A child’s IQ or level of intelligence depends on several factors such as the size of the family, how far apart the children are in age, prenatal factors and not just birth order. Four researchers from the United States, Joseph Rodgers, Harrington Cleveland, Edwin Van, De Oord and David Rowe, addressed and studied large families and the intelligence of their children. They did this by using a national data source, the National Longitudinal Survey of Youth or (NLSY), to assess whether families with children of low intelligence tend to be larger. Not only did they test the intelligence of the children, but they also assessed the mother’s IQ or intellectual ability. The NLSY helped the researchers address whether larger families result in lower IQ’s in children. The information in the report brought the parent’s IQ to their attention as well, which addressed if lower intellectual parents make larger families (Rodgers, Cleveland, Van den Oord, & Rowe, 2000). The researchers examining this study concluded that even though parents with lower intellect have large families, larger families do not in any way make children with a lower IQ. They concluded after studying different types of data and models that birth order does not have an effect on intelligence and that way of thinking is wrong. Aaron Wichman, Joseph Rodgers, and Robert MacCallum did research in regards to a person’s position in the family and what affect that has on intelligence. “Most previous studies compared children from different families, so what they were finding were differences between large and small families, not differences between siblings, according to Wichman” (Grabmeier, 2006, p. 4). He went on to explain that larger families have third and fourth children and coming from larger families will have some disadvantages that may impact the child’s intelligence. They believe that the reality is third born children are just as smart as first born children but some don’t do as well because they are in a larger family. This study involved nearly 3,000 families who participated over a period of 12 years. Every participating child took intelligence tests that measured their skills in math. They also received test on reading recognition and comprehension. They did this study to see if firstborn children did better on test then the younger children, which only a few other studies have actually tested the children within the family. These researchers wanted to ensure accuracy in their findings so they compared the intelligence at specific age points, 7-8 years old and 13-14 years old. This discounts the other studies because the intelligence test was only scored once, with variances in the ages of the children (Grabmeier, 2006). This fact ultimately affects the original study’s results on the effect of birth order. Key components that made this study successful were the researchers using multilevel modeling which allowed them to see the variation in the family and among the siblings in the family. This gave a clear look into environmental influences that might affect intelligence other than birth order. Among the variables is the age of the mother at the time of the birth of first child. “Mother's age encapsulates many variables that could negatively affect the child-rearing environment. The younger a mother was at the birth of her first child, the lower we would expect intelligence scores to be within a family” (Grabmeier, 2006, p. 14).Younger parents sometimes have less income, education and more children, including other factors that can affect the IQ or intelligence of the child. “When the researchers controlled for mother's age at first birth, the effect of birth order on intelligence was nearly eliminated” (Grabmeier, 2006, p. 16). All of these factors play a role in younger children appearing to have lower intelligence, which has little to do with birth order. They are coming from a different home environment then the first-born sibling. They used to variables of mother’s age and family size to control the differences within the families studied, which nearly eliminated the correlation between birth order and intelligence. “Birth order may appear to be associated with intelligence, but that's only because larger families don't have the advantages of smaller families. When examined within families, there is no evidence of any significant association between birth order and intelligence. It's not your birth order that is important – family environment and genetic influences are the really important factors” (Grabmeier, 2006, p. 22). I was raised in a large family myself. I know firsthand how much chaos goes on in a family with more than two children. Being number six out of eight children, my parents did not have time to work with me academically and education didn’t seem to be an important value in our home. I realize now that it was because they really just did not have the time to give me the one on one attention I needed. I personally do not agree that birth order is a factor when we are examining the intelligence of a person. I have five older siblings and I am the only one of them that is completing my college education. In fact, I have to usually guide them on issues in life, even though I am the younger sibling. According to Engler (2014), family constellation refers to your position within the family among your siblings and how your parents are involved with this process. In my opinion, I believe the parent must be involved with their children promoting a healthy lifestyle including building relationships and education. With parent involvement any child regardless of birth order can accomplish their goals and do well academically. There is much debate on birth order and how it affects a person’s intellect. Birth order has been investigated in many different ways. Researchers have studied standardize test scores, polls, academic assessments, family demographics and other factors in regards to birth order. The debate is still unresolved due to disagreements among researchers. Does birth order cause children to have lower intellect or is this caused by factors within the home? My personal feeling is that no child has less intelligence because of birth order; however, parent involvement, home life and factors surrounding their birth can cause children to appear of lower intellect. Researchers and psychologist should definitely consider other factors such as family atmosphere, parenting skills, gender, genetics and what happened during the pregnancy of each child before thinking any child is smarter than the other. References
Belmont, L., & Marolla, F. A. (1973). Birth order, family size, and intelligence. Science, 182(4117), 1096-101. Retrieved from http://www.sciencemag.org.ezproxy.nu.edu/content/182/4117/1096.full.pdf

Black, S. E., Devereux, P. J., & Salvanes, K. G. (2007). Older and wiser? Birth order and IQ of young men. Retrieved November 21, 2013, from http://researchrepository.ucd.ie/bitstream/handle/10197/740/devereuxp_workpap_019.pdf?sequence=3
Grabmeier, J. (2006, November 4). Older children not smarter than their younger sibs, study finds. Retrieved November 22, 2013, from http://researchnews.osu.edu/archive/biorder.htm

Engler, B. (2014). Personality theory: An introduction (9th ed.). Belmont, CA: Wadsworth, Cengage Learning.
Kluger, J. (2007, October 17). The power of birth order, Time volume(issue), page range? Retrieved November 18, 2013, from http://content.time.com/time/magazine/article/0,9171,1673284,00.html

Kristensen, P., & Bjerkedal, T. (2007). Explaining the relation between birth order and intelligence. Science Magazine, 316(5832), 1717. Retrieved from DOI: 10.1126/science.1141493

Paulhus, D., Trapnell, P., & Chin, D. (1999). Birth order effects on personality and achievement within families. Psychological Science, 10(6), 482-488. doi:10.1111/1467-9280.00193
Rodgers, J. L., Cleveland, H. H., Van den Oord, E., & Rowe, D. (2000). Resolving the debate over birth order, family size, and intelligence. American Psychologist, 55(6), 599-612.

Wichman, A., Rodgers, J., & MacCallum, R. (2007). Birth order has no effect on intelligence: A reply and extension of previous findings. Personality and Social Psychology Bulletin, 33(9), 1195-2000. doi:10.1177/0146167207303028