News0 min ago
Brothers and Sisters
What is bizarre that despite the fact that I am male, I have two older sisters, rather than two older brothers. It almost makes me feel that the probability would have been that I would have been born female when I was born, but I was born male instead at the last moment. Talking to my male friends, they say that all have at least one brother and some have no sisters.
It makes me think whether it is something to do with the XX or the XY factor, but in my case it's YY, as in why would I be born male if my sisters were not?
Answers
No best answer has yet been selected by GMH. Once a best answer has been selected, it will be shown here.
For more on marking an answer as the "Best Answer", please visit our FAQ.When a couple have a first child, the probability of it being a boy is approximately 50% (and, self-evidently, the same probability relates to that child being a girl).
Unlike 'toss of a coin' probabilities, however, (where the first 'outcome' has no bearing upon the second), the probability of a second child being the same sex as the first child is higher than 50%. (I can't remember the exact figure but I think it was in the region of 55%-60%).
By the time you come to examine the situation of a couple who already have three children, all of the same sex, the probability that a fourth child will also share that sex is surprisingly high. (I seem to remember a figure somewhere in the region of 75%-80%).
These figures, remember, were cited in mathematics texts which didn't need to find a reason for these events. They were, however, stated as scientific FACTS based upon extensive research. So, while Joko might be correct in saying that GMH's 'reasoning' makes no sense, I feel confident in stating that GMH's 'observations' make perfect sense and fit in with established scientific data.
Chris
A question was posted a while ago (i don't think i could find it again) about what determines whether a baby is a girl or boy. I can't remember which way round it is, but one type is small fast swimming sperm which doesn't live very long (i think they're the boys) and the other is large slow swimming sperm which lives longer (the girls). It depends on the time of the cycle as to which sperm reaches the egg,
i.e. if the boy sperm swim fast and find the egg first it's a boy but if the egg isn't far enough down and the boy sperm die before they reach it or before the egg reaches the right place, the longer living girl sperm catch it.
I'm pretty sure that's right. As for whether you have brothers or sisters, i'm sure it's just pot luck (and perhaps a bit of statistics, etc. as posted above!