>>16837925
51

1 man has a bastard daughter. (2)
He marries his daughter and has 6 sons. (2+6 = 8)
His eldest son impregnates his mom once and gives the father a granddaughter. (8 + 1 = 9)
The eldest son then marries the granddaughter (his daughter) and has 5 daughters with her, the great granddaughters (9+5=14)
5 of the great granddaughters marry their uncles and each have 7 kids (14 + 5*7 =49)
The 1st granddaughter is a cheating slut and gets pregnant two more time bringing her tally up to 7, but no one knows who the father is, maybe the neighbor or family dog (49+2=51)

Wa la. 7 men, 7 wives, each has 7 kids.

How can we further optimize this to get the number down lower?