The results of this analysis partly supported Sulloway’s theories. Firstborn children were, indeed, more conservative on average. However, they were not more likely to be influenced by their parents’ levels of conservatism than their younger siblings, suggesting that older kids aren’t taking on a conservative personality in order to throw in their lot with Mom and Dad.

“In other words, firstborns are more conservative than are second-borns, independent from their parents’ conservative values,” Barni said. This tendency toward conservatism may be a canny way to maintain one’s place in the family, she said.

“Firstborns, having experienced the undivided attention and care of their parents, and being stronger and more intellectually developed than their younger siblings, occupy a dominant position,” she said. “Thus, they tend to safeguard their status advantage by developing conservative values helping them to uphold the status quo.”