All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, is His slave and Messenger.
Perhaps you are referring to the issue of the establishment of the prohibition of marriage between a man and a woman’s female descendants and ascendants if he touches her with lust, or between a woman and a man’s male descendants and ascendants if she touches him with lust. The Hanafi scholars held that the prohibition of marriage is established by this. If this is what you mean, then it has nothing to do with your mother’s marriage to your father. She does not become unlawful to him on account of that, neither according to the Hanafi school of Fiqh, nor other schools. The Hanafi book of Fiqh Al-Hidaayah reads: “If a woman lustfully touches a man, her mother and daughter become unlawful to him. Ash-Shaafi‘i, may Allaah have mercy upon him, held that she does not become unlawful to him as a result. The same scholarly difference of opinion occurs regarding a man touching a woman lustfully, looking at her private parts, or her looking at his private parts with lust.” [End of quote] Therefore, you should disregard this matter completely and devote your efforts to what benefits you. You should not mention this to your parents, nor to anyone else, and you bear no sin for that.
Allah Knows best.