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

[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. ;)

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.