Interpreting lyrics?

Ethan just sang the first verse of a ditty he’s learning in music class:

“There was an old lady lived over the sea
And she was an island queen
Her daughter lived off in a new country
With an ocean of water between
The old lady’s pockets were full of gold
But never contented was she
So she called on her daughter to pay her a tax
Of three pence a pound on her tea
Of three pence a pound on her tea”

When he finished, he asked, “So Mary, can you guess what the song is about?”

She thought for a moment, then blurted, “Puberty?”