How old is this character?

We’re discussing Elizabeth Tallent’s story “No One’s a Mystery”: love/lust/marriage/adultery are the topic of the week, and the readings reflect how various writers and poets (Barrett Browning, Shakespeare, Marvel, Singer, Chopin, Chekov) chose to focus on our basic topic of Love. “How old is Jack,” I ask, “the one who’s been dating the 18 year old girl for 2 years?”
“Too old.” “Eeeeuw.” “That’s creepy.”
“What’s creepy?”
“Well, an old guy and a young…a teenager…” the student shudders. “And they weren’t just dating.”
“Are your mom and dad the same age?”
“They were, but my stepdad’s six years younger than my mom.”
There’s a chorus of reaction to her comment.
According to the class, it’s okay to date someone within a 2-year age span, but anything more is too much. “It’s okay when you get old,” one of them offers. “You know: past say…35 or so.” She considers. “Forty. That’s old enough. Then you can date someone who’s even 15 years older.”
“I’m 20,” another answers. “My boyfriend’s 32. Guys my own age are just too immature.”
“That’s twelve years,” I comment, not mentioning Charles and Diana as a comparison. “So maybe it works? Sometimes? How do we determine when it might and when it won’t – and – taking this discussion back to the story, why do you think it does not work in ‘No One’s a Mystery’?”
Because there is deceit involved, they answer. Because there’s a lack of respect. Because Jack’s closing comment to the narrator, “If you want to know the truth,” intimates as much her reluctance to confront the facts and their expectations spiraling in two directions, as Jack’s past in which he unwillingly learned the truth.
This discussion happens in the classroom, but it’s similar to the consideration that’s part of every story, poem, play. I'm writing a story, and the character in my story is going to be kidnapped. I’ve given the character black hair and blue eyes, an unusual enough combination that other people in the story might notice the character as she crosses the street with her kidnapper. I’ve avoided unusual hair color (red, striped, a coronet of braids) that might pique a lot of interest. I don’t want the kidnapper caught too early in the story, and I want my readers to empathize with an everyday appearance in the kidnapped character. How old is the character? The story is going to develop differently and impact my readers differently if the kidnapped person is 6 or 26, male or female.
How do we explore the gaps of age, background, friendship, and understanding in the relationships we form? Life. Literature. Jack and that narrator confront us with more than a diary, and their fictional future is determined only to a degree by their ages. We’re analyzing fiction and considering perspectives about our own lives and futures. We’re finding our own truth.