Answers to Quora Questions by Yair Davidiy (20 December 2017, 2 Tevet , 5778)
Were people who had Jewish ancestry on their father's side, but not on their mother's side targeted in the Holocaust?
In such cases it was a common practice for a Gentile neighbor or family friend to agree to say that he had had an affair with the mother and the children were his. The authorities would go along with this. I saw an anecdote of the real father being requested by the rest of the family to move away in order not to compromise his Gentile offspring.