Some of fathers’ contributions are surprising. One might guess, for example, that mothers have more influence than fathers on their children’s language development. Despite the growing number of women in the workforce, mothers still spend more time with children in many families than fathers do.

But that turns out not to be the case. Lynne Vernon-Feagans of the University of North Carolina, who studies language development, has found that when it comes to vocabulary, fathers matter more than mothers.

In middle-class families, she found that parents’ overall level of education — and the quality of child care — were both related to children’s language development. But fathers made unique contributions to children’s language development that went beyond the contributions of education and child care.