Even as a child, Siegfried Wagner seemed out of step with his parents.

Nevertheless, here’s the charming story behind the “Siegfried Idyll,” a work named for him by his father.

The idyll was composed shortly after Siegfried’s birth, in1869, and presented as a surprise gift by the composer to Siegfried’s mother, Wagner’s new bride, Cosima (recently divorced from conductor Hans von Bülow, a Wagner champion, who had tolerated their affair).

In a supreme romantic gesture, Wagner unveiled the work on Christmas morning, with his musicians arrayed along the stairs leading to the master bedroom of their Swiss villa. Wagner had it played for Cosima every year as an expression of his love. It had been his original intention to keep it private, within the family, but then cash ran short, as it almost always did, and he was willing to change his mind. Themes from the work would also be reused in the Ring Cycle.

The original title of the piece was not quite so snappy. At the time the music was first presented, the score bore the inscription: “Triebschen Idyll, with Fidi’s birdsong and the orange sunrise, as symphonic birthday greeting. Presented to his Cosima by her Richard.” Fidi, of course, was the Wagners’ nickname for their son, born 150 years ago today.

Hear Siegfried conduct the serenade named for him by his father, in this 1927 recording.