Danny was a pretty young dad....
I'm just binge watching this show and DJ is ten. Around S1 episode 9 or 10, Danny flips out about turning 30. He states he also bought his car 10 years ago. That means he had DJ at 19 or 20, had enough money to buy a classic car while quite young, and support a family. Granted there was a 5 year gap until Stephanie, and a 4 or 5 year gap until Michelle. I think he stated somewhere he'd been married or was with his wife for 13 years.... So he maybe married at 17?
He talks about wild times in that car too, and not really alluding to his wife with those stories.
He also managed to go to college through all this too and have a pretty well decked out house (even if he didn't initially pay for it).
I could be wrong, but.... Wow. He was a bit of a lad.