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?

Presumably it's a tendency to produce more than one egg, which a father can't do?

Right, but PC's asking if that gene can be passed on from the father.

I don't know the actual genetics behind this, but I do know that Mendelian genetics doesn't exactly apply to us. Some genes depend on which parent you got them from. I assume this is why, say, breast cancer, can only come from your mother's family.

Identical twins are completely spontaneous - no inherited tendency. Tendency to non identical twins are inherited as mother releases 2 eggs and she passes that tendency on to her daughters (obiosly cannot pass it on to son) That's what I've heard anyway - my aunt was a twin, my h's uncle is a twin - H is non identical twin - so no increased chance of twins for me

OK there are two types of twins, identical and non identical. I dentical comes from one egg and one sperm 'splitting' into to separate babies. This type of twin does not run in families

Fraternal twins happen when a mother releaces two eggs in a cycle, these are fertilised by two sperm. This type runs in familes, it is the 'I can release two eggs' trait that runs in familes. Mum does the egg, dad makes millions of perm, so only the mum 'carries' a greater liklyhood of having twins

Yes, of course the father can't do that, but couldn't he pass that ability on to his daughters?

Good question

Hmmm tamum, where are you

well we've got twins on both mum and dad's side - my dad's an identical twin (one other set in his family) and mums got 4 sets in her side incl her brothers.

(one of her twin bro's I might add, went on to have a twin PG with his wife but one twin m/c at 17 weeks)

is there a link then?

Really NQC? I didn't know that. (Lots of stuff I don't know - lol! ) But men can get breast cancer too - is it a different cancer to the women's sort?

No, it's the same sort, I think.

I should have been more clear. Both genders can get breast cancer. But you can only inherit a tendency towards breast cancer on your female line. (Not everyone who gets breast cancer has a genetic tendency to it.)

Of course, there's always mitochondral DNA, which only travels down the female line. But I don't think it has anything to do with breast cancer or twins. I could be wrong.

Munz, I don't think identical twins run in families, so your dad's family is probably just a fluke. Your uncle's twin PG was caused by his wife releasing two eggs (unless it was an identical twin PG? hard to know), which of course is down to her genetics, not your uncle's.

interuterine environment having an effect?

@ordinary' monozygotic cross can't explain it.

TAMUM!!!!

Hi, I have started a twin relate thread as there is a possibilty that I could have twins as my maternal grandmother was a twin (non-id) and my mother didn't have them and my sister can't have children.

My SIL had non-id girl twins 2 months ago with this history:

Her father's mother was a twin which shouldn't pass down. Her H had a twin who died, his mother is a non-id twin, her mother was a twin. Therefore technically she shouldn't have had twins!!!! I think.

but that's just it

dads side (identical twins)
mums side - 1 set b/g (was the b that m/c apparently) 2 set identical 2 sets non identical incl the dad of the m/c twins - at a loss! lol.

is it true twins 'skip' a generation?

jersey, you can still have twins without any related twins. It does happen. Lots of factors cause women to release multiple eggs, not least of all is age - the older a mother is when she gets pregnant, the greater her risk of twins.

And of course, like any random thing, sometimes twins just happen.

I'd heard that afro-carribean women more likely to have twins...

Oh well let you know in Jan when I get my scan if I'm carrying twins or not!

identical twins def dont run in families. They aren't really sure what genes causes fraternal twins, although it is thought that hormones are important. (fsh or follicle stimualting hormone) fsh is necessary for egg growth and also used for fertility treatment. Mothers of fraternal twins tend to be taller, habe earlier and shorter period cycles. Since these are female hormones and genetics it is impossible for it to be passed down the male side of the family.

there weren't ne twins in my family before mine. africans do have a higher occurance of twins - twice as likely as white women I think. Asian twins are the rarest - half as many as white women.

Kelly, I think the incidence of twins is higher in some African groups, but not all. The genetic diversity of African people is higher than that of any other "race" - that's the most significant "racial" genetic difference.

Also, I am sure that some sex-oriented stuff passes down via the other line - e.g. men tend to get their balding patterns from their mum's dad, IYSWIM. So it isn't quite as simple as you suggest.

Where is tamum?!?

What are you saying NQC? This is terrible! Don't tell me my gorgeously red-headed ds is going to start going bald in his 30s! Hang on a sec - I think you may be mistaken, my mum's dad only started losing his hair in extreme old age, whereas my dad and my borther started classic male-pattern baldness in their thrities. Phew! There is hope yet for ds's mop.

PC, I don't think the male balding thing is guaranteed. But it certainly can be inherited that way.

Is anything guaranteed in genetics?

We do like things to be cut-and-dried nowadays.

Two blue-eyed people can't have a brown-eyed child.

But yeah, generally, genetics are a bit more complicated than that.

NQC - where are you getting your breast cancer info from? - The most common gene found to be mutated in familial breast cancers is BRACA1 if I recall correctly - it is on chromsome 17 and a mutation can be inherited from a father or a mother - however, a mother who carries a mutation may well have breast (or related) cancer. If you look at a family tree and mark off the relatives with breast cancer you will find that they are female because it is the interaction of the genetics and the enviroment (ie. oestrogen in a female body) that gives rise to the cancer...but it doesn't mean that males can't carry and pass on the gene mutation.........

I'm joining in with the shouts for TAMUM!

There is a 'parent of origin' effect in genetics - a gene can be switched on or off depending on which parent it is inherited from - but these genes are pretty rare.. Also of course, there are genes on the sex chromosomes X and Y which can lead to disorders being more common in males than females ( if they are carried on the X chromosome then females have a spare copy if the gene is faulty - males will just have one faulty copy and therefore will have the disorder).

Genetics is so much fun

sh*t, really?

I read it somewhere, and have been holding onto it, as one of my paternal aunts died of breast cancer.

I did read it ages ago, though, so it may well be outdated.

Ok, will ask oncologist BIL or surgeon SIL (specialising in breast cancer) sometime soon.

There certainly are some things that are inherited in a sex-linked way, even if breast cancer isn't one of them.