By four years, iirc.
I’m My Own Grandpa
Dwight Latham, Moe Jaffe
Oh, many, many years ago
When I was twenty-three
I was married to a widow
Who was pretty as can be
This widow had a grown-up daughter
Who had hair of red
My father fell in love with her
And soon the two were wed
This made my dad my son-in-law
And changed my very life
For my daughter was my mother
‘Cause she was my father’s wife
To complicate the matter
Though it really brought me joy
I soon became the father
Of a bouncing baby boy
This little baby then became
A brother-in-law to Dad
And so became my uncle
Though it made me very sad
For if he was my uncle
Then that also made him brother
Of the widow’s grown-up daughter
Who of course is my step-mother
Chorus
I’m my own grandpa
I’m my own grandpa
It sounds funny I know
But it really is so
Oh, I’m my own grandpa
My father’s wife then had a son
Who kept them on the run
And he became my grandchild
For he was my daughter’s son
My wife is now my mother’s mother
And it makes me blue
Because although she is my wife
She’s my grandmother too
Now if my wife is my grandmother
Then I’m her grandchild
And every time I think of it
It nearly drives me wild
For now I have become
The strangest case you ever saw
As husband of my grandma
I am my own grand