Of course, I agree with you. It's just by referencing the 20 year old age, I was thinking about the circa age when the wide majority of people start their careers (20-25). But like I said in my original comment, there are those exceptions of cool people that started hacking late in life and your dad is certainly one!
I still think the assumption that hacking started with programming is wrong, there've been countless hackers, they were just generally confined to physical media (eg: engineers). And I don't think making the transition towards software wasn't all that radical for most.
[edit: typos]
Yes of course. I was referring to software hacking like the original post.
He doesn't program any more, but the idea that you'd have to be 20 when you started is just plain wrong. You could've been 40.
He also used to play with meccano and legos, and I remember we built a traversing crane during a Christmas in the mid 80s (on ropes from the living room to the kitchen, a spam of some 7 meters). If you were a hacker soul before personal computing, it'd be quite easy to get into computers (and realize that it would be important).