I wrote to you for your birthday last month, but I have not heard from you ever since.  Although I addressed you as “my dear boy,” I also noticed that you were getting kind of old. Gosh, you turned twenty-three this year! Among other things, I asked you for your opinion about my book concerning climate change, which you requested and received soon after it appeared in print last year, but which you never commented. I closed my happy-birthday message with a few words about your sister and my daughter, with whom I have lost touch already. I sent her my hugs and kisses through you in hope of hearing from her soon. And I closed my message with the standard phrase I have been using for years: “daddy loves you very much.” But I received not a peep from you. So, just as I wrote to your sister last year, from now on it will be up to you (“Up to You: An Open Letter to My Daughter,” October 17, 2014). As I wrote to her, parents and children often fail to understand each other, and there is little that can be done about it. As for the coming years, it is up to you. And you alone. Whenever you decide to resume communicating with me, I will be there for you. And that is my belated birthday gift to you, too. Enjoy!