From what I learned, she was promiscuous and charmed. She slept with Nicholas II when she was 17 and he was 22. She even said he was a virgin. I don't think he was a father. The affair ended when he was married and became a tsar. She went on to seeing other Grand Dukes Andrei and Sergei. My guess is Andrei was a father because the son looked like him. Andrei and Sergei were convinced they were a father. She seemed convinced Andrei was a father, but Sergei's name was on the son's birth certificate. I guess we will never know.
If Nicholas II married Mathilda, their children would have not inherited terrible genetic disorder, hemophilia.
