boys and girls The answer (assuming any particular kid is equally likely to be a boy or a girl) is surely exactly 1:1 - it doesn't matter who's having the babies, and what their reasons are for continuing to breed or not - that's just a red herring. Unless families are actually killing the girls, the number of boys and girls in the country will be the same number who were born, and there's no reason for any one particular baby to be more likely to come out male. So no maths is required to convince yourself that it's 1:1. Chris Harris Wednesday, April 27, 2005 Actually the proportion is 52:48. There are slightly more boys born than girls. Stephen Jones Wednesday, May 04, 2005 Yeah i thought that might be the case. Hence the assumption. But then it seems to me that the proportion will be the same whatever criterion the parents use to decide whether to have a baby (unless it involves some kind of genetic test/screening to check/affect the likelihood of them having a boy). Is this the case? E.g. say instead people only stopped having kids if and when they had twice as many boys as girls - what would the expected proportion be then? It seems less intuitive then but i reckon it'd still be 52.48% or whatever Chris Harris Wednesday, May 18, 2005 Yea, you're right. I was only being pedantic. What does happen in both India and China is that they kill the girls, either before or just after birth. Stephen Jones Sunday, May 22, 2005 Slightly  more boys are born than girls but boys have a higher mortality rate.  So by the end of the first year the ratio is about even. In any particular age group or band the ratio changes over time.  Boys die off faster than girls (in general) so by age 50 there is a large population of girls vs boys. As someone else pointed out in certain countries modern technology has made the situation worse.  If you know the gender of the baby before it is born (eg ultasound) and abortion isn't illegial and you have a strong cultral desire to have a particular gender then that creates a large skew. Some have even posited that in a decade or so there may be more homosexuality in certain countries due to the lack of females.  I don't think so because all the scientific evidence points to that behavior as genetic.  I just think prostitutes are going to make a fortune in those locals. Jim Kennedy Monday, May 23, 2005 I've actually heard in the past that Girls have a slightly higher birth rate due too the X chromosome sperm cell being slightly larger and more resilient then the Y chomosome, but its been some time since I have done any reading on the subject. Kristian M. Pownall Friday, June 03, 2005 It is unfortunate that India and China have female infanticide cases - but the subtle or open - discrimination will take its toll. At any case  there are more men to women who work and earn. Lets talk about these numbers and compare how this will affect the future x Saturday, June 04, 2005 I've heard that if intercourse occurs significantly before ovulation girls are more likely and as time goes it skews towards boys. The "speedy-y, hardy-x" theory was once popular but seems to have evidence which discredits it... WanFactory Friday, June 17, 2005   Fog Creek Home