Twins and genetics

Jags8

I'm really curious, who here knows the genetics of twins? I'm always shocked when women think they could have twins because they run in their husbands family. A woman on October '14 recently posted about being pregnant with twins and thinks it's because they run on her husband's mother's side. DH's grandma recently told me that I might have twins because they run in her family. I had to explain that identical twins are a fluke and do not have a genetic link, and that her genetics wouldn't dictate how I ovulate in order to have fraternal twins.

So, who here already knew this? Who is like "whoa, I didn't know that!"?

mnicolew

I knew this, though I am intrigued how often twins do tend to pop up when there have been twins on one side or the other before. 

Edited for typo.

Ducktale

Nicb13 said:

Fraternal twins come from 2 different eggs released at the same time right? I thought that women can inherit that ability to release multiple eggs and that was the only thing that was genetic. I guess I never looked into it much honestly.

Where is Joy?!

I thought this too. Fraternal twins are rampant in my mom's family so I've always been a little paranoid I might have twins. Because, you know, twins are totes gag-worthy and all.

Jags8

Nicb13 said:

Fraternal twins come from 2 different eggs released at the same time right? I thought that women can inherit that ability to release multiple eggs and that was the only thing that was genetic. I guess I never looked into it much honestly.

Where is Joy?!

Yes that is correct, fraternal twins can be genetic. But my DH's genes wouldn't dictate how I ovulate. Therefore it doesn't matter if twins runs in his family.

24karat

Yep I knew about this already. Granted, I have twins myself.

It's amazing how many misconceptions there are. Countless people have asked if I could have b/g identicals, if they run in our families, etc.

Sliptak

Innnnteresting! I have definitely heard that myth before and just kind of accepted it without thinking but after you just explained that it's like DUH! Especially since I knew that twins come from releasing multiple eggs and OBVIOUSLY that would have nothing to do with the father, let alone his genetics. 

spalko

I always understood it as you inherit the genetic ability to hyperovulate (tendency to release multiple eggs during ovulation). I've read that men can be the carrier for the hyperovulation gene which explains twins skipping a generation. If Grandma has twins - Dan & Stan - they can carry the hyperovulation gene, men don't ovulate so less likely to have twins (excluding other factors), thus skipping that generation. Their daughters, however, may end up having twins.

Sliptak

spalko said:

I always understood it as you inherit the genetic ability to hyperovulate (tendency to release multiple eggs during ovulation). I've read that men can be the carrier for the hyperovulation gene which explains twins skipping a generation. If Grandma has twins - Dan & Stan - they can carry the hyperovulation gene, men don't ovulate so less likely to have twins (excluding other factors), thus skipping that generation. Their daughters, however, may end up having twins.

oh that makes sense...@jags8 thoughts?

Jags8

Sliptak said:

spalko said:

I always understood it as you inherit the genetic ability to hyperovulate (tendency to release multiple eggs during ovulation). I've read that men can be the carrier for the hyperovulation gene which explains twins skipping a generation. If Grandma has twins - Dan & Stan - they can carry the hyperovulation gene, men don't ovulate so less likely to have twins (excluding other factors), thus skipping that generation. Their daughters, however, may end up having twins.

oh that makes sense...@jags8 thoughts?

Yep that is accurate. A father can pass the gene onto a daughter. But a father cannot cause twins himself.

lifeonthehill

Good God. H is from a family full of twin sets. Unfortunately he is a part of the only set who actually both lived. Him just barely. I would be happy to have twins but get really overwhelmed at the thought. I am so excited that it is not up to him.

I feel bad when his family tells me twins are in our future! I just smile and nod. Haha.

Meery82

Yes, I knew this. Fraternal twins=two separate eggs, two separate sperm. No different than non-twin siblings. Identical twins are one fertilized egg that splits. Two exact replicas. No genetic predisposition; complete freak of nature.

I have fraternal twin cousins on my dad's side. I would like to have one more baby, but apparently I could end up with more. 

:-S

JocelynB0911

Like others have said fraternal twins are caused by the mother hyper-ovulating. That gene can be passed down.

I have twin boys and let's say once they get married and start a family they wouldn't have a higher chance of twins (unless the wife had released two eggs) but if they had a girl she could be a recipient of that gene.

Identical twins are a fluke of nature. It's a single egg that splits early on.

Helenahhandbasket

I did know-- and I am also shocked that people don't know-- including a woman I work with who herself is an identical twin.

She was convinced either she or her sister wold also have ID twins.  Neither did.

NerdyLucy

There is a couple I know that have two sets of identical twin boys.

I said to someone in my family, "Wow, what are the odds of two sets of IDENTICAL twins?"  I was stressing the concept of identifical.  My aunt, who works with the wife/mother of the couple, said, "Actually, if you have one set of multiples, there's a higher chance of another set of multiples."

I just kind of nodded because I don't know enough about it to say anything, but I figured what she said could potentially be more true for fraternals, not identicals. My first instinct is that she's wrong, but again, I'm relatively ignorant about twins.

Of course, it could just be an assumption by everyone that they're all identicals. I mean, I thought the Olsen twins were identical when they were little, but according to them and their family, they're not.  

I grew up assuming that the doctors could just tell during the pregnancy what type all twins were, but I now know that it's not necessarily that easy. I occasionally lurk on the Multiples board and see this kind of thing being discussed.

 

NerdyLucy

Jags8 said:

spalko said:

I always understood it as you inherit the genetic ability to hyperovulate (tendency to release multiple eggs during ovulation). I've read that men can be the carrier for the hyperovulation gene which explains twins skipping a generation. If Grandma has twins - Dan & Stan - they can carry the hyperovulation gene, men don't ovulate so less likely to have twins (excluding other factors), thus skipping that generation. Their daughters, however, may end up having twins.

oh that makes sense...@jags8 thoughts?

Yep that is accurate. A father can pass the gene onto a daughter. But a father cannot cause twins himself.

I'd always been curious about this.

I have adult fraternal twin cousins, a male and female,and the male is the father of fraternal twin boys.  In my family, of course, it's assumed that the twins are due to their father being a twin, but obviously that may not be the case in their situation. Heck, maybe his wife has fraternal twins in her family. I have no idea.

 

I think twin genetics is a fascinating topic.

Jags8

@NerdyLucy, the Oleson twins aren't identical?! I always assumed they were. I graduated high school with identical girls who I can easily tell apart. I also graduated with fraternal twins guys who I still can't tell apart!
As far as your cousin who is a fraternal twin having fraternal twins...they could run in his wife's family, or she could just happened to have released more than one egg that cycle. Either way, there is no possible way that your male cousin could have caused his wife to release more than one egg.

NerdyLucy

Jags8 said:

@NerdyLucy, the Oleson twins aren't identical?! I always assumed they were. I graduated high school with identical girls who I can easily tell apart. I also graduated with fraternal twins guys who I still can't tell apart!
As far as your cousin who is a fraternal twin having fraternal twins...they could run in his wife's family, or she could just happened to have released more than one egg that cycle. Either way, there is no possible way that your male cousin could have caused his wife to release more than one egg.

I agree.  I could never convince my family of that though.

 

Also, yeah, I had always assumed they were identical (Olsen twins), but I've read numerous articles and interviews where they say they're fraternal.  I actually can tell them apart now, but when they were kids? No way.

JocelynB0911

NerdyLucy said:

Jags8 said:

spalko said:

I always understood it as you inherit the genetic ability to hyperovulate (tendency to release multiple eggs during ovulation). I've read that men can be the carrier for the hyperovulation gene which explains twins skipping a generation. If Grandma has twins - Dan & Stan - they can carry the hyperovulation gene, men don't ovulate so less likely to have twins (excluding other factors), thus skipping that generation. Their daughters, however, may end up having twins.

oh that makes sense...@jags8 thoughts?

Yep that is accurate. A father can pass the gene onto a daughter. But a father cannot cause twins himself.

I'd always been curious about this.

I have adult fraternal twin cousins, a male and female,and the male is the father of fraternal twin boys.  In my family, of course, it's assumed that the twins are due to their father being a twin, but obviously that may not be the case in their situation. Heck, maybe his wife has fraternal twins in her family. I have no idea.

 

I think twin genetics is a
fascinating topic.

-------------------------------

The female doesn't necessarily have to have fraternal twins on her side of the family to have multiples. Just because you carry the gene that causes hyper ovulation doesn't mean you will end up with twins. Does it make your chances higher? Slightly. Fwiw, I don't have twins on my side of the family and my twin boys will be 6 months this Friday.

JNCPro3130

I had never thought much about it.  I know the difference between the two, but not the genetics behind it. I thought both were caused by genetics... Don't I feel smart.  ">

24karat

Another thing to note is that many times fraternals aren't spontaneous, they are due to IVF or other fertility treatments. So one could have fraternals in your family and not have the hyperovulation gene. The US inclusive twinning rate is 3% which means the spontaneous rate is even lower.

SmileyJay

haha yes I am constantly shocked by how little some people know on the subject.

Maybe I just know more than average (and have for most of my life) because fraternal twins run in my family. 2 sets on dad's side, 1 on moms. Also a set of identical on dad's side but that is a fluke like you said. We have a pretty small family, so that is a lot of twins within just the last couple of generations. No fertility treatments or anything like that. 

I think twins are an adorable blessing but I would never wish for them because of how difficult the pregnancy usually is. Plus, two babies is very tough on new parents! I freak myself out because I frequently have ovulation pain on both sides and worry I will release two eggs when we conceive. Fingers crossed for only singleton pregnancies in my future!

Hats off to all ladies that have given birth to and raised multiples!!

SmileyJay

It would just be spontaneous that a male who is a twin or has twins in the family would have twins himself. He releases millions of sperm but that won't make there be more than one egg. Twins all have to do with the egg... rather more than one is released (hyperovulation) or the egg splits early on to make identical twins. 

But like you said, most people have a really odd understanding of how conception and twinning works and don't know this. 

Another odd topic - I have fraternal boy/girl cousins that are about my same age. Growing up, it was always apparent that the boy was very feminine and the girl quite masculine. Not sure if I'm using the right words - but you get what I mean. Not just interests but also facial features and body type. Anyways, as adults she is a lesbian and her brother still comes across as effeminate although he identifies heterosexually. To be clear - we love them both dearly and they are both completely amazing. Wouldn't change them for the world. I have just always found it interesting how there seems to be a biological "mix up" of sorts. Anyone else know of a pair of twins like this?

CowgirlK39

Knew all this, but i have a background in biology so I've known for a long time. @TheCraftyKoala, I have personally known cases like the twins you mentioned. There was a study done years ago and God help me I can't recall it completely so take this with a grain of salt, but there was discussion of hormonal interference from both twins occasionally being a factor. Like i said, i do not have that info on hand but im sure someone can find it with some digging. In cows, having M/F twins is a bad thing. One of them will be born sterile, but there is no way to know which till they are sexually mature so both are culled. They are known as freemartins.

DebateThis

kjkarats03 said:

Another thing to note is that many times fraternals aren't spontaneous, they are due to IVF or other fertility treatments. So one could have fraternals in your family and not have the hyperovulation gene. The US inclusive twinning rate is 3% which means the spontaneous rate is even lower.

That's not completely true - it's a very common misconception. Higher rates of multiples are seen with fertility medications and to some extent, IUI. IVF actually carries the lowest rate of multiples of any ART (assisted reproductive therapy). Oral meds like clomid (unmonitored), followed by injectible meds like Follistim cause significantly higher-than-average rates of twins, whereas IVF twin rates in <35 women are only a couple percentages higher than average because IVF allows for the control of the number of embryos transferred and other methods of ART do not.

Pookieson

I knew this only because I'm a hyperovulator.  I don't know why though.  As far as I know there are no twins on either side of my family except on my moms side and they are identical.  My 1st PG I lost a twin at 9 weeks but carried DD to 28 weeks.  My mmc I lost two.  I'm hoping this time for just one because I obviously am not very good at carrying two of them.  

Wine&Cupcakes

spalko said:

I always understood it as you inherit the genetic ability to hyperovulate (tendency to release multiple eggs during ovulation). I've read that men can be the carrier for the hyperovulation gene which explains twins skipping a generation. If Grandma has twins - Dan & Stan - they can carry the hyperovulation gene, men don't ovulate so less likely to have twins (excluding other factors), thus skipping that generation. Their daughters, however, may end up having twins.

I believe this to be true. My mom was pregnant with twins x 2 (lost both pregnancies) so I think she may hyperovulate. Makes me a little apprehensive to think that perhaps she does, and perhaps it could be inherited...but yes, it's all about the gene being passed on for fraternal, and, from what I understand, identical are spontaneous splitting.

blush64

I am also surprised at how many people don't know more about twins. I know identical twins just happen but I have had a lot of people wonder if I thought I might have twins since twins are in the family.

I do have many twins all through both sides of my family but they are identical for the most part. In my immediate family my father is an identical twin and my sisters are identical twins, I suppose that throws some people off and they assume it must be passed somehow.

Edit DaisyBlinks, I had heard that somewhere as well but I have no idea where so I don't know how credible it was.

I guess if they eventually discover it is not just a fluke it won't be shocking.

SmileyJay

@cowgirlk39 - thanks for the info. I realize for some people that probably sounds really odd, but I have always thought genetics had to play a huge part in it. In the case of my cousins, the differences were apparent from very early childhood. They are both happy, healthy adults now but I'm not sure about sterility as neither of them have children. Really interesting topic though!

SmileyJay

Also - I remember growing up and going places like the zoo with boy/girl cousins. People would ask if they were identical even though they could tell it was a boy and a girl. Very odd and my aunt would always laugh and say "yes!". 

Helenahhandbasket

DaisyBlinks said:

Ok, so what I've heard/read online somewhere is that identical twins MAY not be just a fluke of nature. That really, no one knows if there's a reason for it. And they MIGHT 'run in families' through the father because sometimes identical twins can be seen throughout family tress. Something genetic in the dad's sperm could be causing the fertilized egg to split. 

So...I have no source for that, I don't know where I heard it and I don't even really believe it. But I can sort of believe in the possibility. 

This is so interesting!

DebateThis

DaisyBlinks said:

Ok, so what I've heard/read online somewhere is that identical twins MAY not be just a fluke of nature. That really, no one knows if there's a reason for it. And they MIGHT 'run in families' through the father because sometimes identical twins can be seen throughout family tress. Something genetic in the dad's sperm could be causing the fertilized egg to split. 

So...I have no source for that, I don't know where I heard it and I don't even really believe it. But I can sort of believe in the possibility. 

It's been noted for at least a decade and it's true in some cases, haha. Some women produce eggs that have a thinner than average zona pellucida (the "shell" of the egg) and when it's thinner it makes an egg more prone to splitting into two.

barely

I'm always shocked when people try to guess the sex of their child or future children based the mother's siblings/family....what?? How do you not know that the sperm determines sex?!? I l learned that in like 6th grade. Seriously though..... 

Eta: not the same thing, I know, but similar....

alllouise

Yikes my dad IS a twin, he has a twin sister. Neither of my aunts two girls had twins... and there's me and my sister... She's had two boys so far (not twins) I am yet to conceive so we will see

SmileyJay

@barely5feet - I think there has been some research that women do play a part in the sex of the baby due to their acidity levels. A more acidic environment is said to favor female sperm that are more hardy than males. Shettles method is based on this, even though it has been dis-proven quite a bit. So although the sperm is what determines the sex of the baby, the conditions in the mother may favor x or y sperm. 

Not sure I believe this, but I have heard it!