"Yy" is not a standard term in genetics or any other field. It's possible you meant something else, or there's a typo.

To help me understand what you're asking, could you please clarify what you mean by "Yy"?

For example:

* Are you referring to a specific genetic trait?

* Are you asking about a specific type of individual?

* Is "Yy" a code or abbreviation for something else?

Once I understand what you're asking, I can provide you with a helpful answer.