Participants will complete the experiment online at [faceresearch.org][1] on their own computer. There are two parts to this experiment, a questionnaire and a kinship judgment task. The questionnaire is a sibling questionnaire, where participants indicate the number and age of their own siblings. [View questionnaire interface][3]. For the kinship judgment task, each participant will be presented with 132 stimuli pairs, which are presented in a random order. Participants receive the following instructions: > In this experiment you will be shown 132 pairs of faces. Some are siblings, some are an unrelated pair. You will be asked to determine whether each pair is “unrelated” or “related”. After the experiment, you will be told how many of the 132 pairs you correctly determined and what the average performance on this task was. <p> Subsequently, there will be a short questionnaire about your family composition, e.g. how many siblings you have.</p> They will judge if each pair is related or not by clicking on buttons labelled "related" or "unrelated". [View kinship interface][2]. The trials will be self-paced. [1]: http://faceresearch.org/project?ratersibs [2]: https://osf.io/rh7sf/ [3]: https://osf.io/cxwp8/