Textual and Musical Differences in the Rhyme

The text of this rhyme itself varies considerably from version to version. It is interesting to find such variety in one rhyme. In comparison, The Queen of Hearts rhyme text remains nearly identical in numerous versions over a long span of time. In Hot Cross Buns, the rhyme begins:

"Hot Cross Buns!
Hot Cross Buns!
One a penny, two a penny,
Hot Cross Buns!"

Some versions end there. Others follow with one of the next two lines:
"If you have no daughters, give them to your sons."
Or,
"If your daughters do not like them, give them to your sons."
Finally, the last two lines of the rhyme are sometimes included, sometimes not:
"But if you haven't any of these pretty little elves
You cannot do better than eat them yourselves."

Why so many varieties? Could it be that different versions were spawned as the rhyme was adapted to music? That would explain why The Queen of Hearts, which is more of a poem, remains more intact. The music, too, varies from version to version. Compare these two pieces of sheet music and this website's musical version:

Mr. E's Virtual Music Classroom This professor at the University of New Brunswick, Canada, has built an instructional site all about the rhyme Hot Cross Buns which includes a third musical version of the song, different from the ones above.