I have heard a lot that aggression is a genetic trait that can be breed out by selective breeding. However I saw a YouTube video where a guy claimed in the description that aggression is a learnt trait and he had left offspring with aggressive parent and all the offspring turned out nasty but when he took the litters from an aggressive parents and had them fostered by non-aggressive parents that all the babies turned out non-aggressive as well. I don't have any ASF yet but I found that interesting and wanted to see if anyone else has done this or has any knowledge of such?