A study done by BYU found that siblings might become more different over time as a result of their parents’ beliefs about them and the comparisons they make between them. The study looked at 388 teenage first- and second-born siblings and their parents’ beliefs about them. What they found was most parents believed their oldest did better in school even though most siblings’ achievement was very similar.
“Parents’ beliefs about sibling differences weren’t influenced by past grades, but future grades by the teenagers were influenced by the parents’ beliefs.” There was a 0.21 difference in GPA the following year with the child parents thought was more capable doing better than their sibling. Over the years, this difference can continue, making a bigger impact.
There was one exception to the trend though; if the oldest was a brother and second-born a sister, parents believed their daughter was smarter. This seemed to be true when comparing grades; sisters usually had better grades than their brothers.
To best set our children up for success, “parents should focus on recognizing the strengths of each of their children and be careful about vocally making comparisons in front of them.”
For more information see: https://news.byu.edu/news/parents-comparisons-make-siblings-different
Image from: https://www.parentmap.com/c/51b0d6be/images/stories/Rotators_Verts_2011/0611_siblingrivalry_rotator.jpg