The relation between having siblings and children’s cheating and lie-telling behaviors

•Time impact of having siblings on children’s dishonesty was examined.•Children who had a sibling were more likely to cheat than children without a sibling.•Children with a younger sibling were more likely to lie as the age difference increased.•Children with a younger sibling were better able to maintain their lie. The current study investigated how having at least one child sibling influenced children’s dishonest behaviors. Furthermore, for those children with a sibling, we examined whether having a younger or older sibling and the age difference between siblings influenced deceptive acts. Children between 3 and 8 years of age (N = 130) completed the temptation resistance paradigm, where they played a guessing game and were asked not to peek at a toy in the experimenter’s absence. Children’s peeking behavior was used as a measure of cheating, and children’s responses when asked whether they had peeked were used as measures of lie-telling. Results demonstrate that siblings do indeed influence children’s deceptive behaviors. First, children with a sibling were significantly more likely to cheat compared with children without any siblings. Next, for those with a sibling, children with a larger age difference with their younger sibling(s) were significantly more likely to lie compared with children closer in age, and children with a younger sibling were significantly more likely to maintain their lie during follow-up questioning compared with children with an older sibling.