Individuals share approximately 12.5% of their genes with their first cousins, who can be an important part of social and kin networks. However, cousin relations have been relatively understudied. Using data from contemporary Finland, we investigated contact frequencies with first cousins in 2 adult generations (older generation, born between 1945 and 1950, n = 1,778; younger generation, born between 1962 and 1993, n = 1,669). In addition, we studied whether individuals without siblings have more contacts with their cousins than individuals with siblings. In both generations, women had more contacts with their maternal cousins than men. Women also reported more contacts with their maternal than paternal cousins, although this matrilateral bias was not found among men. Furthermore, in the older generation, women without siblings had more contacts with their cousins than women with siblings. Our discussion of these findings refers to evolutionary behavioral theories predicting differences in kin investments. (PsycINFO Database Record (c) 2019 APA, all rights reserved)

Impact Statement

Public Significance Statement: The present study found that among older and younger adults, women have more contact with maternal cousins than men. Women also have more contact with maternal than paternal cousins. Moreover, older adults without siblings reported more contacts with cousins than older adults with siblings. These findings illustrate that the commonly found matrilateral and sex biases in kin relations are also present in cousin relationships. (PsycINFO Database Record (c) 2019 APA, all rights reserved)