Про папу Кушнера все понятно, а вот биография его дедушки по прозвищу "Hatchet Joe" покрыта тайной:
https://puppet-djt.livejournal.com/67520.html

С дедушкой Трампа проще. Обжуливать правительство своей страны и уклоняться от службы в армии - это у них потомственное https://yakov-a-jerkov.livejournal.com/1371532.html?thread=45843084#t45843084

Friedrich Trump, a German, was issued with the document in February 1905, and ordered to leave the kingdom of Bavaria within eight weeks as punishment for having failed to do mandatory military service and failing to give authorities notice of his departure to the US when he first emigrated in 1885.
https://www.theguardian.com/us-news/2016/nov/21/trump-grandfather-friedrich-banished-germany-historian-royal-decree