Stop in for a cup of coffee

It's kind of funny. My son also has this internal clock, he's up at 7 every morning happy and ready to go. My daughter on the other hand is like my wife, wake her up before noon and you're fighting Godzilla
I wonder how that works? I used to get up to Milk the cows and then to drive truck for another 14 years and I am still getting up. Or is it something born in ya