My monthly stupid question!!

Indeed. And while it would be possible for one male to produce two absolutely different sperm the odds against it would be astronomical.

Not only would you need to produce two entirely different sperm (I'm not sure that is possible) you would also need to impregnate two Ova to produce two viable embryos to be able to test to find out whether they were indeed different.

The odds must be totally mind-bending.

The same is true of genetics generally. It is actually statistically possible that two completely unrelated people could have identical DNA. However being statistically possible and actually happening are two very different things.
 
Quoted for emphasis. I'm amazed seriously worried someone believe two sperm fertilising one egg = twins.

Why? Assuming he's not a geneticist, the information is unlikely to ever be of use to him.

Besides, it does produce twins. They're just frequently non-viable or suffer significant defects. A search at Google throws up a Time article from 2007 about a pair that was carried to term. One appeared fine, the other had ambiguous genitalia. The article suggested that this was big news and of significant research value, so from the sound of it this is not well understood stuff.
 
Last edited:
On a slight tangent which lightly incorporates the OP, how come a baby is considered viable if born at 23 weeks but you can have an abortion at 24 weeks? Surely the latest abortion date should be set below the minimum viability date?

An abortion that late would be for medical reasons - i.e. severe danger to baby or mother.

In 2004, there were 185,415 abortions in England and Wales. 87% of abortions were performed at 12 weeks or less and 1.6% (or 2,914 abortions) occurred after 20 weeks.

http://en.wikipedia.org/wiki/Abortion_in_the_United_Kingdom#Statistics
 
Last edited:
An early teen who attends a biology class can tell you this...

Given how much maths knowledge people appear to retain beyond school, I don't think what people are taught at school is a good measure of what knowledge people can be expected to have.

Besides, I said it would not be of use to him, not that he'd not been taught it.
 
Not only would you need to produce two entirely different sperm (I'm not sure that is possible) [..]

Now you've piqued my curiosity. I know only a very simplified model of how it works, so I could be missing all sorts of things:

Chromosomes in pairs (un-matched in the case of an X and a Y)
Each pair is one from each parent
Each sperm is a pick 'n' mix of one from each pair of chromosomes.

But for two sperm to be entirely different, every gene would have to be different. I don't know enough to know whether that's just very unlikely indeed or actually impossible.

Can anyone satisfy my curiosity?
 
cound't the genes in the sperm be different just due to random mutations? i mean i always assumed that they would all be different as it's not a digital process so no identical copies. i mean, i thought that in some small tiny way that they would be different in some way. even if it's not really an important one.
 
Now you've piqued my curiosity. I know only a very simplified model of how it works, so I could be missing all sorts of things:

Chromosomes in pairs (un-matched in the case of an X and a Y)
Each pair is one from each parent
Each sperm is a pick 'n' mix of one from each pair of chromosomes.

But for two sperm to be entirely different, every gene would have to be different. I don't know enough to know whether that's just very unlikely indeed or actually impossible.

Can anyone satisfy my curiosity?

23 chromosome pairs
Each sperm picks 23 at random
2^23 = 8,388,608 = lower bound assuming perfect copying
The trouble is copying isn't perfect, so you get mutations, and things happen like bits going from one chromosome to another, so the odds end up far beyond that.
 
Closely related to the question the OP raised.. had an interesting discussion with a friend about this and we did some stats the exact odds of our existence:

1.2 trillion sperm are produced on average by a man in his lifetime, and 400 eggs from a woman. You were one sperm and egg combination, and assuming that your concious being is controlled by your genetic makeup it's safe to assume that if your sperm hadn't won that day and reached the egg you wouldn't exist, certainly not in the capacity you do now and perhaps not at all. You had a 1:480000000000000 chance of existing. On top of that you were born into the one of the richest most developed societies in the world, dodging about 82% of the global population who don't have money in their bank or a roof over their head. So you had an 8% chance to have the oppurtunity you have today, disregarding the fact that you're even alive.

The estimates and figures are very rough, but it gives you an idea of how special your life is, no matter how you're choosing to live it, or how it has been thrown at you. If infinite truly exists then you could theorise that no opportunity is alone, but it still makes you appreciate that opportunity a little more.
 
What?! I thought the stolk brought along babys when mummys and daddys crossed there fingers and asked nicely?!
 
Back
Top Bottom