gender_ratio.py

from __future__ import division
import random

# question: consider a society that allows only a single child,
# unless your first child is a girl, in which case you can have
# one more child. does this policy introduce a male gender bias?

N = 1000
boys = 0

for _ in xrange(N):
  if random.randint(0, 1) > 0: # is a boy
      boys = boys + 1
  else: # first child is a girl
      N = N + 1
      boys = boys + random.randint(0, 1)

print("Boys: %d, Girls: %d" % (boys, N - boys))

# => Boys: 732, Girls: 268