As it was mentioned in the comments, Ken’s newfound son Lawrence is played by William Roache’s real son, Linus. Linus Roache is one of those actors who’s not a huge star but he shows up in lots of things like Law & Order, Priest, and, in Batman Begins, played Batman’s father, Bat-Dad.
Also, turning up this week is Lawrence’s son, who’s played by James Roache who is also William Roache’s son. In The Road to Coronation Street, James played his father.
So Ken’s son is his real son but his grandson is also his son and his grandson is also Ken. Got that?