Question for the mathematically inclined

[plural]

Statistically the
frequency of occurrence of
Twins (either fraternal or identical)
being born to one set of parents
by volume of total children conceived

or
in other words

if I wanted to have
39 children
statistically speaking
how many sets of twins
would I be likely to have?

Comments

[petermarcus.livejournal.com]

The odds don't look good, my friend. Statistically, maybe one set.

Read this. (http://uwphysicians.org/hbeat/hb971202.html)

[strike-anywhere.livejournal.com]

according to this () the probability of a twin birth is 1/90 (I suspect that this may be lower if you have a set of identical twins, since you may then be predisposed to have them, but let's not quibble...).

We can then (this is, of course a silly model, but the simplest) think of these being independent (this assumption is violated because of the genetic question above) bernoulli trials. This then gives the distribution of the number of twins in a sample of 39 bernoulli trials as a being a binomial distribution.

It can be verfied that the expected value of this distribution will be 39*(1/90)=13/30=0.43333.

NOTE: I can provide more specifics if you wish.

Bah

[zaiah.livejournal.com]

I know of a modern family with one set of triplets and two sets of twins and only two other single births without the use of hormones.. If he's a carrier for identical twins they've a good shot. ;)

remember, I'm on cold medicine

[kansaschica.livejournal.com]

My grandfather's mother had 11 children. 6 of those were twin-sets.

I know that's way higher than average. And I don't know of any other twins in my family's geneology.

So, while that can offset the 1 set in 39 kids theory, I also knew in school, there'd be (at any given time) about 5 sets of twins in my class (meaning all the same grade year, not one single class of 30 students). My graduating class, so give or take, it was still about this, was 739.

So, using those odds... divide 700 (to round down, since this isn't exact science) by 2.

350. 5 of every 350 were twins, or 1 out of every 70.

Sooooo... given all the differences in genetics, bladda bladda...

I think if you have 39 kids, you'll probably have 3 sets of twins, or 2 sets of triplets.

thought process is courtesty of generic brand cough and cold syrup that's running through my brain. So don't pick me apart. I'm likely to cry or go into a coughing fit right now.

Re: Bah

[strike-anywhere.livejournal.com]

that was my point with the 'genetics' comment...

I think it's the mother that needs to have the predisposition for multiple births however, since a twin comes from either a split of the egg after fertilization or two being released by the ovaries and both being fertalized...

In any event, the probabilities of twins *given* a certain number of twins seen wasn't available... had it been, the numbers would have been very different indeed.