It's fascinating to me how some people can keep it so separated. There's a guy on my team who, earlier this summer, messaged me on a Monday and said, "Hey I need to take two weeks off starting tomorrow.". I asked if everything was okay, and he assured me that it was. I said that because of the length of time and short notice that it had to go above me for approval. He was fine with that, and said if HR needed to know that it was because his wife had had a baby the night before. After I submitted the request, my boss was asking me how I didn't know that this guy's wife was pregnant, (because the company tries to send a gift.)
I told my boss that not only had he never shared with anyone that he was going to be a father, he'd never shared that he was married at all. The guy was just incredibly private. He wanted no congratulations. Didn't want anyone else on the team to know. Super nice guy. Good at his job. Very friendly and sociable. Participates in outings and get togethers. Just likes to keep things entirely separate.