^It's basically a rule that the youngest you're supposed to date is your age divided by two plus seven.
Well that's a little better than the method I use, where I consider anyone 18 years younger than me is off limits. The formula above allows me to consider someone 38 instead of mid-40s. I stopped buying Playboy after the centerfolds were being born the year I graduated high school.
There were also other moments when the writers hinted at Jake with older women (that woman who forced him to write to drain his energy had sexual imagery). And this was in the early seasons. He was still a minor IIRC?