Do whatever you decide you want to do to "keep up" with github, open source, etc. But keep it absolutely as separate as possible from your family time.
When you have a day with the kid, make sure that you disconnect and get yourself as fully as you can into the right mindset. "My job today is to enjoy my time with my son/daughter, to be there for them, to be present with them." Leave your phone at home when you go to the park. Disconnect.
If you find yourself thinking that your parenting time is an annoying distraction from the coding problem you're trying to solve, you're in dangerous territory and need to re-calibrate.
This is a hard lesson that I constantly try to re-learn. When I'm successful, everything is much, much better.