Early morning warriors (or lunatics)

I wake up between 4:00 and 5:00 every day and am writing shortly thereafter.

This morning I was out of bed at 4:10. 

My brother texts me every morning around 5:00. He wakes up a little earlier than that to get ready for work. He’s typically in his office (by choice) by 6:00. 

This morning his text arrived at 4:55.

I just learned today that my sister wakes up at 4:30 and writes until about noon. Sometimes later. She writes researched-based content for companies that are attempting to improve their SEO by increasing their online presence.

This morning she emailed me at 5:49. 

Three siblings who rarely see each other, all awake before 5:00 AM and working.

It must be genetic. Right?