This is an open-access article distributed under the terms of the Creative Commons AttributionNonCommercial 4.0 International License (https://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and reproduction in any medium for non-commercial purposes, provided the original author and source are credited, a link to the CC License is provided, and changes -if any -are indicated.© Abstract. The present research examined attitudes towards cousin marriages among young people from various ethnic groups living in The Netherlands. The sample consisted of 245 participants, with a mean age of 21, and included 107 Dutch, 69 Moroccans, and 69 Turks. The parents of the latter two groups came from countries where cousin marriages are accepted. Participants reported more negative than positive attitudes towards cousin marriage, and women reported more negative attitudes than did men. The main objection against marrying a cousin was that it is wrong for religious reasons, whereas the risk of genetic defects was considered less important. Moroccans had less negative attitudes than both the Dutch and the Turks, who did not differ from each other. Among Turks as well as among Moroccans, a more positive attitude towards cousin marriage was predicted independently by a preference for parental control of mate choice and religiosity. This was not the case among the Dutch. Discussion focuses upon the differences between Turks and Moroccans, on the role of parental control of mate choice and religiosity, and on the role of incest avoidance underlying attitudes towards cousin marriage.