This is a song about fictional people who used to farm near a place I used to fish,” James McMurtry says from the stage before launching into “Deaver’s Crossing,” a track off Complicated Game, his first studio album in nearly seven years. It’s a head-scratching bit of banter, which is not surprising coming from a songwriter whose lyrics lean more toward the imaginative than the confessional. Standing beside him, harmonizing and playing guitar, is his son, Curtis, a recent graduate of Sarah Lawrence College who studied composition and spent much of his time there writing contemporary chamber music. Last summer Curtis, who was born and raised in Austin, released his debut album, Respectable Enemy, a collection of songs that aren’t chamber music but sound nothing like his dad’s songs either.

If you’d wandered by chance into this late-December gig at the South Austin coffee shop Strange Brew, you might not have taken the men onstage for father and son. Dark curls spill down James’s shoulders, just as they did on the cover of his 1989 debut, Too Long in the Wasteland, though his unruly goatee is now more salt than pepper. Curtis, who stands a few inches shorter, is mostly clean shaven, and his own curls are closely cropped. Where James slouches, hulking over his red Guild acoustic, Curtis stands tombstone-stiff while playing the same model in green.

For the next half hour, the son and grandson of Texas’s most-beloved living author swap songs and exchange badinage. “You told me that you can’t write a song about one girl,” James says, shooting Curtis a look. “You’ve gotta do a composite of about five of ’em.”

“I did tell you that,” Curtis admits.

“I realized you were right,” James says, flashing a rare grin.

After their brief set, father and son sit catty-corner from each other in a closed-off section of Strange Brew that doubles as a green room. The differences seen onstage are even more apparent in conversation. Curtis talks eagerly about growing up listening to his dad write songs and remembers that rough drafts of lyrics taped to the living room wall were a common sight. James, as befits his somewhat cranky reputation, is less chatty (a billboard in Austin advertising the new record calls him “the most disinterested man in the world”). But he opens up when asked about his son.

“He’s got a lot more intricate taste than I do,” James says. “He was trying to teach me some stuff today, and he said, ‘You don’t use a lot of diminished chords, do you, Dad?’ And I said, ‘No, pretty much straight cowboy chords for me.’ ”

Curtis sings backup vocals and plays banjo on Complicated Game, marking his third straight appearance on his father’s studio albums—he played baritone sax, of all things, on 2005’s Childish Things and 2008’s Just Us Kids. Neither McMurtry can pinpoint the precise date they first shared a stage, but both agree it was one of James’s gigs nearly a decade ago at Austin’s Cactus Cafe, when Curtis was in his early teens. “He had me play mandolin and tenor guitar—bunch of stuff I can’t play at all,” Curtis recalls. “I had to earn my keep.”