If a Jewish man had a son from a non-Jewish woman, and this son later converted to Judaism, what's the halacha regarding his relationship with his biological father. A convert is כקטן שנולד and unrelated to his parents, but is that the case when his father is Jewish? Will he inherit his father? If his father was a rebbe, will this convert be next in line???
Mishneh Torah (Issurei biah, 12:7) states that there is no relation even prior to the child's conversion
שֶׁהַבֵּן מִן הָעֶרְוָה בְּנוֹ הוּא לְכָל דָּבָר וּבִכְלַל יִשְׂרָאֵל נֶחְשָׁב אַף עַל פִּי שֶׁהוּא מַמְזֵר וְהַבֵּן מִן הַכּוּתִית אֵינוֹ בְּנוֹ שֶׁנֶּאֱמַר (דברים ז':ד') כִּי יָסִיר אֶת בִּנְךָ מֵאַחֲרַי מֵסִיר אוֹתוֹ מִלִּהְיוֹת אַחֲרֵי ה':
For a child conceived from any other forbidden sexual union, is [the father's] son with regard to all matters and is considered a member of the Jewish people, even if he is a mamzer. A son conceived by a gentile woman, by contrast, is not considered his son. [This is derived from Deuteronomy 7:4:] "For he shall sway your son away from following Me." She turns him away from being one of those who follow God.