"...sibling shares are decreasing with birth order...children from larger families have lower levels of education and that there is an additional negative birth order effect."
Booth, A., & Kee, H. (2009). Birth order matters: The effect of family size and birth order on educational attainment. Journal of Population Economics, 22(2), 367-397. doi:10.1007/s00148-007-0181-4
This piece explains the effect of family size and birth order on the educational attainment of children. Even though research used to write this article was obtained in Europe, I still feel that this information has relevance in the United States. This is an academic article that cites several other sources to support its research, therefore I know it is a reputable source. Also, I would use this quote in particular to explain why younger siblings struggle more than their older siblings in school. Though I would also make the claim that depending on how close in age these siblings are, the case isn't always this drastic, with my sisters and I used as an example in this.
"...birth order is influential in development because of both (a) differential investments by parents and (b) children's finding a niche in the family... the effect of birth order on personality is mediated by niche finding and differential investment."
Dunkel, C., Harbke, C., & Papini,
D. (2009). Direct and indirect effects of birth order on personality and
identity: Support for the null hypothesis. The Journal of Genetic Psychology, 170(2),
159-75. Retrieved from
This piece discusses the effects of birth order on personality and identity. This study was also conducted in Europe, but the information collected is valid, as results are presented along with the use of other sources to back-up the arguments. Results show that the effects of birth order are still fairly controversial because of the mixed findings, but that niche finding and differential investment mediate it. I could use this article to show that despite the results found, information is not conclusive because results from different studies conflict with each other.