Donald Trump Jr. was physically abused by his father, so much so that Jr. is reputed to have been called Diaper Don because he drunkenly wet the bed so frequently. His friends always felt sorry for him because he was drunk and stumbling or falling down all over the UPenn campus. His friends attribute it to the physical abuse of Donald Jr. by his father. They described an incident when Trump came to pick up Donald Jr. for a baseball game and when he opened the door to his father wearing a Yankee jersey, Trump Sr. slapped him across the face knocking him onto the ground in front of his friends and told him to put on a suit and meet him outside. 
This is the kind of man Donald Trump is--a man that beats up and humiliates his own son in front of his peers.
This is the kind of man that white Americans chose because mainstream white American culture at heart is a violent and soulless culture. You could see this sad fact from videos of Trump rallies.