Selfish traits are more pronounced in firstborn (Image: Cheyenne Glasgow/Getty)

FIRSTBORN children are more likely to achieve greatness, but this may come at the cost of a less trusting, uncooperative disposition.

We know that firstborns are generally smarter than their younger siblings and more likely to become leaders, while younger brood-members tend to be more rebellious. To see if trust in adults might also be affected by birth order, Alexandre Courtiol at the Institute of Evolutionary Sciences in Montpellier, France, paired 510 students with anonymous partners to play a finance-based game. Both players were given 30 monetary units and …