Выпуск 1305. Внебрачный сын Леонтьева?

The woman is sure that her deceased brother could not have a son from a mistress. However, the mistress claims that they had a serious relationship, the man recognized the child, and even planned to leave his wife. Is it possible that the man concealed his illegitimate son from his family? Or did the mother of the 9-month-old son simply choose a convenient father?