Which of these would be used as a dividing line between the northern and southern hemispheres?
a. the equator
b. the north pole
c. the south pole
d. the prime meridian

answer; no longer than a reasonable period of time;

a family can go through many changes which would make it complex. having children can cause a change and increase the complexity. this would change the distribution of authority and management, as the older siblings will at some point be in charge of the younger ones, and discipline must be distributed when they get in trouble.