Author Topic: An Adult Should Really Know This - Silly Things You've Had to Tell People  (Read 303876 times)

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RingTailedLemur

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I am amazed how many people mix up "physicist" and "physician".

greencat

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The Notalwayslearning that made me try to reach through my screen and beat the "knowledgeable" one with the Shovel of Knowledge was this one:

http://notalwayslearning.com/it-was-a-cownjugal-visit/30532

 - while "sperm" is not an acronym for anything, it is actually an abbreviation for the word "spermatozoa."

TootsNYC

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I think some (not all) people may feel that way because they hear some (not all) New Yorkers say "Well in New York, we..." like they want to feel separate from the rest of the US.
[/quote

New York City can be VERY different from other types of locales. But so can the deep country; so can a suburb; so can many other cities.

But we're still America.

mbbored

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It doesn't matter that there's twins in your husband's family, you won't be having twins.

Are the "likelihood of twins"-gene only passed down through the maternal side of the family?

I've never found a definitive answer for that (i.e. the likelihood of your daughter having twins if there are twins in your husband's family) but nothing your husband can do can make you release two eggs.

Very true, but it might be possible that something your husband can do can make the egg split into two embryos. So identical twins might still be possible.

From what I've read the general opinion is that identical twins don't run in families.

Fair enough - I wouldn't have a clue :) I've just heard that twins run in families, but had no idea about the specifics.

From what I understand, identical twins are the cause of a spontaneous split in the zygote and isn't related to the genetics of the parents. Fraternal twins are due to a woman ovulating two eggs at a time and are a genetic trait in the mother's line; it can't be due to the father. However it can be passed down to the mother by her father. For example, I have a friend who's father and aunt are fraternal twins. She and her siblings aren't twins, but she and her sister have both given birth to fraternal twins.

Shalamar

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I'm embarrassed to admit that I've had the "Are they identical?" conversation about boy-girl twins - with me asking that question.  :)    My only defense is that I didn't really mean "identical"; I meant "Do they look exactly like each other, except one's obviously a boy and the other is a girl?"  (Thinking Bobbsey Twins here.)  Of course, in that case, I shouldn't have used the word "identical". 

Pen^2

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Yes, identical twins are due to a single fertilised egg splitting into two separate eggs before they each develop separately. The twins come from the same original egg and sperm. They are thus genetically identical; they are naturally occurring clones. Fraternal twins are when two eggs happen to ovulate at once and both end up being fertilised. The twins are genetically not the same (since they came from different eggs and different sperms), and are nothing more than ordinary siblings.

Since gender is determined by DNA, identical twins will always have the same gender, barring a sex-change. Fraternal twins can be whatever, just like any other pair of ordinary siblings.

How about: the difference between astrology and astronomy. I was teaching a class about the solar system, and a disturbingly large number of the kids' parents thought, based on the unit name, that we would be learning about gemini and sagittarius and all that. Some rang up to ask why we would be spending so long (4 weeks) on it.

RingTailedLemur

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How about: the difference between astrology and astronomy. I was teaching a class about the solar system, and a disturbingly large number of the kids' parents thought, based on the unit name, that we would be learning about gemini and sagittarius and all that. Some rang up to ask why we would be spending so long (4 weeks) on it.

Aaaaaaarrrrrrrrgggggggghhhhhhhhhh!

ClaireC79

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That no, boy/girl twins can NOT be identical. The standard question after learning my twins are boy/girl is, are they identical? I always reply nicely that, no, they aren't, but I've had a few people ask me if I'm sure!

I've had to explain this to a few people recently. One seriously thought that gender was determinded during mid pregnancy and you could have itentical twins of difference genders because the egg split before gender was determinded.

I have seen a photograph of conjoined twins of different genders - I think the final conclusion was that they should both have been male but one must have had a faulty Y chromosome so looked female (but would have been the same as a girl with Turners syndrome XO instead of XX)

kherbert05

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I have two friends that are twins and have a strong family resemblance - but are not identical. They had to argue with DOCTORS that they weren't identical - they had different blood types.
Don't Teach Them For Your Past. Teach Them For Their Future

kareng57

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I have two friends that are twins and have a strong family resemblance - but are not identical. They had to argue with DOCTORS that they weren't identical - they had different blood types.


I believe that there's another type of twins - the egg splits before being fertilized by two different sperm.  So they'd have the same genes from Mom, but different ones from Dad.  I too once knew girl twins who I always assumed were identical till the mom mentioned that they weren't - I wonder if that's the scenario.

Then again, it's possible to non-twin siblings to have a very strong resemblance.  Years ago in the neighbourhood there were two sisters two years apart in age - and I couldn't tell them apart unless they were standing next to one another.  (I didn't know them very well, otherwise I'm sure I would have learned).

m2kbug

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I have two friends that are twins and have a strong family resemblance - but are not identical. They had to argue with DOCTORS that they weren't identical - they had different blood types.

I believe that there's another type of twins - the egg splits before being fertilized by two different sperm.  So they'd have the same genes from Mom, but different ones from Dad.  I too once knew girl twins who I always assumed were identical till the mom mentioned that they weren't - I wonder if that's the scenario.

In this case they would still share a placenta, so it would probably be hard to tell right away, unless one was a boy and one was a girl.  I imagine this is pretty rare. 

One question I used to get as a kid, "How do you tell yourselves apart?" ;D 

ClaireC79

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identical twins don't always share a placenta it depends on when the embryo splits

Outdoor Girl

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Probably one of the best examples of fraternal twins and definitely not identical would be the Roloff twins from Little People, Big World.  One is normally sized and the other is a little person.
I have CDO.  It is like OCD but with the letters in alphabetical order, as they should be.
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greencat

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I have to admit my own silly thing.  A friend of mine recently had to tell me that my impression that every country in Europe drives on the left side of the road was quite mistaken.


Also, I know a pair of genetically identical twins who are not physically identical - I know non-twin brothers who look more alike than they do.  One twin is 4 inches taller than the other and somewhat more "masculine" looking features.

Weirdly, now that I think about it, my biology class's unit on twins went something like "The Peters twins are identical.  The Johnson brothers are fraternal twins who don't look alike.  Amy and Mark Smith are fraternal twins who look a lot alike, but are a boy and a girl, so you know they have to be fraternal."  I went to school with a lot of twins!

HoneyBee42

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It doesn't matter that there's twins in your husband's family, you won't be having twins.

Are the "likelihood of twins"-gene only passed down through the maternal side of the family?

I've never found a definitive answer for that (i.e. the likelihood of your daughter having twins if there are twins in your husband's family) but nothing your husband can do can make you release two eggs.

Very true, but it might be possible that something your husband can do can make the egg split into two embryos. So identical twins might still be possible.

From what I've read the general opinion is that identical twins don't run in families.

Fair enough - I wouldn't have a clue :) I've just heard that twins run in families, but had no idea about the specifics.
My research (after having spontaneous fraternal twins) revealed that identicals have about the same odds of showing up (it's somewhere around 1:285 pregnancies).  Fraternal twins, barring fertility drug use (which skews the figures to a ridiculous degree) have variations that seem to differ by things like maternal age, ethnicity (there's apparently a Nigerian tribe with a 1:22 chance of fraternal twins).  For me, the odds were 1:90 ... and I was that 1.  My daughter, by virtue of being a fraternal twin has a 1:17 chance that she will be the mother of twins.  And yes, the only way to have a set of identical twins of opposite genders is if there is a defect in the chromosome for one.

(I can't even begin to tell you how many times, when my twins were infants, I was asked if they were identical .... *AFTER* saying that it was a girl and boy in the stroller.