Why do twins only run on the mother's side?

[PrettyCandles]

Surely a father could carry the twinning gene and pass it on to his singleton daughters?

yeah they can nqc, i was surprised too

This link is a really nice explanation of the inheritance of breast cancer.

www.genetichealth.com/BROV_Breast_and_Ovarian_Cancer_in_Families.shtml

Please notice that inherited breast cancer is really really rare - and that the cancer has to have occured at a young age to 'count'.

Sorry to have worried you NQC.

Eh, it was stupid of me to just stick to what I'd heard ages ago.

I don't know how old my aunt was when she first got sick. 40s? Maybe? Is that young for breast cancer?

Back to twins for PC

According to this www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=OMIM&dopt=Detailed&tmpl=dispomimTemplate&list_uids=276400

The scientific jury is still out on the inheritance of non-identical twins - there are thoughts that it is multi-factorial, involving more than one gene - not just the 'produce more than one egg' gene but a 'and babies survive to term' gene...40% of non-identical twin pregnancies end up with only one baby at term (A couple of my friends have found that they had lost a twin at their first scan) - so it's not just the ability to 'make twins' but the ability to keep them that needs to be inherited.

Generally the 'youth' criteria is under 50....please look at the link and see just how rare it is! Please try not to worry.

I left out a _ between the BROV and breast and between in and families - grrr copy and pasting grrrr.

Hello

I can see no earthly reason why the tendency to fraternal twins couldn't pass through the paternal germline, as Prettycandles says, but it's not something I know much about I'm afraid. Breast cancer genetics is something I know a lot about and I'm afraid you are completely mistaken, NQC. Sorry. There are no "breast cancer genes" that can only pass through the female side, and the pattern baldness stuff is largely an old wives' tale too.

Bluebear and mb, you were doing fine on your own

bluebear, you did put the _s in, but mumsnet interpreted two of them as a reason to underline some words. Here it is as a direct link.

At any rate, I see your point, my aunt's cancer was almost certainly sporadic, not inherited, as none of her sisters, her mother, or my cousins have or had breast cancer as far as I know. It's a big family, so there are lots of samples. (Oh, and that aunt was a big drinker, which seems to be a factor.) If she was under 50, she wasn't much under 50 when it started.

Oh, and regarding your paternal aunt, you would really not be considered at high risk- it has to be two second degree relatives or one first degree relative before they start thinking about a genetic risk generally. I wouldn't worry too much, honestly.

No stress tamum, good to have our official expert on these things around. MB and bluebear did seem to be doing a good job ...

Maybe the "twins only run on the mother's side" thing really is an oversimplification based on the fact that only the genetic history of the woman affects a couple's chance of producing fraternal twins?

Humm... this is fascinating! I should know tha answer,but I don't!

Traits that are passed only by the mother are traits determined by genes in the X chromosome that are recessive and therefore needs two copies ( and 2 X chromosomes to be expressed).

However, recent studies have suggested that non-identical twins is caused by a gene on chromosome 3....

So, bluebear is right is probably multifactorial with some kind of trigger in the X chromosome if indeed passed`only by females....
But multifactorial genes don't tend to be passed by females only...

I'm baffled! I'm supposed to be a geneticist!

lua, I hate to say it, but if something is X linked recessive and needs two copies then it has to have been inherited from the father's side too, and therefore not only passed on by the mother surely?

Very glad that you have peace of mind again NQC..phew!

(Now I should get back to writing my essay ...it's on genetics..does this count as research? )

Hell, I would say it counts as work, wouldn't you

it would be interestign if it does run down both side, my dd's dad is a twin, his mother and father were both twins and I've had twins. She could be pretty likely to have them then, couldn't she?

Sounds like she might be in line for quads

dont say that!!!! as my mum is an non-identical twin!

Tamum - it's almost work - except that I'm off sick today - the kids have given me a horrendous cold - but I would like to finish my essay.....maybe after another cup of tea .

Wow Kelly- what a lot of twins! My Dad is a twin..but an identical one so just a twin by chance.

Tamun - you are absolutely right about the inheritance.
I was thinking about what would look like "female - linked".

tamum - 2 second degree relatives? Are these aunts and cousins?

lol, well as you know tamum, I have one first degree relative and 1 second degree relative who had breast cancer!

I really must get myself down to the genetics clinic.

That's right Tinker, or grandmother. Mother or sister is first degree (I think!).

weesaidie, you're very young yet It would be worth going at some point though

Hmm, aunt and her daughter both had/have breast cancer.