Yes, we all get anon was also communicating that his dad didn't contribute ~half of anon's genetic material, but using language that also communicates that real parents should be devalued if they don't contribute their seed and seed donors should be thought of as being more than just irrelevant seed donors.

You would be technically correct with the first two even though I was talking in social terms,not technical ones, but adopted kids are not step-kids. Those aren't are legally full parents, not step-parents. Step-parents might be the boyfriend or next husband of a single mother or vice-versa, but once you are adopted, if we are getting pedantic about it, the step thing disappears.