plenty of Fathers and sons, and even grandsons in NZ flying helicopters, or planes. Some in Military, many not, as our military isn't that big. Maybe a bit of aptitude for similar types of occupations, maybe something else.
I look at it like sports. The number of Fathers, sons, cousins etc that have played for the All Blacks, or other top sports teams, must say something for genetics, determination, or maybe its all nepotism!