### Collection Procedure Saliva samples will be collected for genotyping and HLA-analysis. Samples will only be collected from participants if both participants in a pair give consent. As participants enter the lab, they will rinse their mouth out with water. Samples will be collected 30 minutes to 1 hour after this. Participants will not be allowed to eat, drink, smoke or chew gum in this time. Saliva samples will be collected using the Oragene DNA (OG-500) collection kits following the instructions included in the package (http://www.dnagenotek.com/ROW/products/OG500.html). Step 1. of the instructions will be read to participants and the experimenter will verbally confirm that participants understood. The tube will be given to the participant and they will be given ample time to fill the tube with saliva to the required level. The experimenter will ensure saliva reaches the required level before completing the process (Steps 2 to 4). #### Instructions in package: 1. Spit until the amount of saliva (not bubbles) reaches the fill line. 2. Hold the tube upright with one hand. Close the funnel lid with the other by firmly pushing the lid until you hear a loud click. The liquid in the lid will be released into the tube to mix with the saliva. Make sure the lid is closed tightly. 3. Hold the tube upright. Unscrew the funnel from the tube. 4. Close tube tightly with small cap. Shake for 5 seconds. Discard the funnel. Once collected, samples will be stored at room temperature between 15-30 degrees Celsius. For an analysis plan and additional hypotheses unrelated to the KINSHIP project, see osf.io/hfqav .