there is nothing mentioned about the portion of people who want boy as a child. Until we know whats the probability of a given couple desiring boy as a child, we can’t proceed. If we assume half of them desiring boy as a child and half desiring girl, then due to symmetry , proportion of boys to girls must be 1.
Actually it doesn’t matter whether a couple wants boy as desired child or a girl, the expected number of boys is always equal to expected number of girls. For example if all existing couples desires boy as child , the expected number of girls after any time is equal to the expected number of boys. this can be easily seen from the convergent series
0*(1/2) + 1*(1/2)**2 + 2*(1/2)**3 + ...inf whose each coefficient denotes the probability of having i girl children before getting a boy child, times i. clearly it converges to 1 meaning that expected number of girl children before getting at max one boy child is 1.(we are assuming here that couple desires boy as their child)