How do I add a topic to my profile?

I think I just found out!

You can click on topics you find on anyone e’se’s questions. Or you can add a new topic by adding it to a question of your own. The topics you add, and the questions you answer, affect the questions you get in your “Just For You” list.

Adding a topic to your question does not automatically add it to your profile, which you can probably see. In order to add a topic to your profile, you need to hover over the topic in the questions and then click “add topic”. Once you do this, the topic is added to your profile and will show up on your profile for others to see as well. Then, any question that is tagged with a topic you have added to your profile will appear in your “questions for you”.