I understand. I think. I may have had a similar feeling when my younger daughter and I received our DNA results from Ancestry.com and found out she was half English and Scottish when we were told she was at least 75 percent Eastern European. We believed my in-laws when they told my ex that his birth mother was a 16-year-old unwed mother from a “nice Jewish family in Chicago. She wasn’t. She wasn’t even 16. She was an unmarried 26. And through my daughter’s DNA we found my ex husband’s birth father and all his relatives.
I was excited to tell Jon, my ex. Well, he didn’t want to know anything about “those” people. He said they meant nothing to him. He said he loved his adoptive parents, who are both gone. They raised him, took care of him, loved and protected him, and he had “no need” to meet anyone who gave him away.
And here’s something else. His last name Colman was made up. I think that’s even less of a “real” name than your father taking on his step father’s name. His family name was Cohen and was changed when his Uncle Alex began manufacturing women’s apparel. Alex Cohen of California sounded “too Jewish.” And before Cohen, back in the old country, it was Moscowitz. I thank God it was changed!
I don’t want to be a Moscowitz. Colman is fine. I briefly remarried and took on the name Gunther, hated it (it sounded too “German German German”) and made it Colman-Gunther, dropped the Gunther and went back to Colman. Actually I took back my “German German German” maiden name, Reich (which was a made up name, too). I think whatever name you have lived with is part of your heritage, however it came to be. And hell, if you aren’t happy with it, pick a pseudonym you love. Don’t let this affect your writing. Don’t let what could really be an insignificant pebble in your path get in your way.