BTK Killer: How Come No One Knew?

How can a guy keep files on his victims, spend time tracking them and no one, not even his family, has any idea?

"I'm amazed … that nobody was able to figure out that this guy
had this secret life that he was hiding."
Psychologist Dr. Howard Brodsky

Oh, I'll bet someone did. The neighbor he constantly hastled hated him. I'll bet he tortured his family in arcane, hard to justify ways: making them late for engagements all the time, showing up on his own schedule for dinner then yelling at his wife because she didn't wait, tongue-lashing the kids for not doing a chore right, nit-picking and harassing and haranguing and sarcastically pointing out faults. I'll bet this guy majored in the minors to distract from being a total bench-warmer in the majors--so average and obnoxious I bet he didn't even get in the game.

Even being a serial killer, if he had been a loving, warm and nurturing husband and father, surely his wife and children would visit him simply to ask, "Why dad?"

I have this funny feeling they don't visit because the already know why--they got to live with him for years and hated him for reasons they never could put their finger on. Now everyone else knows too.