Microsoft founder Bill Gates congratulated his youngest daughter Phoebe on her 20th birthday with old childhood photos. “One of the greatest joys in my life is watching my kids grow into great adults,” the 66-year-old wrote on Instagram on Wednesday. “Happy Birthday @phoebegates. I’m so proud of you.”

In the photos, Phoebe can be seen, among other things, as a little girl with her father. Billionaire Gates has two daughters and a son with his former wife Melinda. Phoebe’s sister Jennifer got married last fall.