What is the probability for a couple of having a daughter if they have
to boys from the first two preganancies?

The reason for asking is that I have been told that if you already
have to boys your are much more likely to have another boy than a
girld. The reason for this could be a selection of viable sperms
favouring male gender if you already have sons. 

If you had two girls previously then likevise you would have a greater
chance of having another daughter than a son.

I am interested in an answers that goes beyond highschool statistics
of flipping the coin with demographic references of the answer.

Many thanks :-)

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Clarification of Question by pedersen-ga on 28 Mar 2005 11:28 PST

to boys = two boys

You may find this article to be of interest:

http://www.public.iastate.edu/~chance99/144.rodgers.pdf

No.  Your sample size (2 children) is too small to predict anything
compared to the population of sperm cells involved, and the number of
possible outcomes (two, male or female) is too limited for most cases
to hold much meaning.

Some couples may be predisposed to have a specific gender child, but
highschool statistics (if that is the right grade level) will tell you
that a sample of 2 out of a population of millions of sperm/egg
combinations is too small to tell if a particular couple has a bias
toward either gender.

Even if a majority of couples were only able to have children of a
single sex, you don't have enough information to suggest that the
exact couple in question is one of those couples.

YES!

I cannot support this with any 'scientific' evidence except that it's
an Old Wives Tale that has been fully tested by Time.

It all depends on the couple involved and the predominat genes they
throw. Each couple is different and each person within the couple as
well. DNA is what will decide the sex. As the body chemistry changes
with age, health, outside influnences, etc. it will effect the result.
My family had 3 males(dad +2 uncles) then my aunt. I have three
brothers and 1 sister(brothers 1st,2nd, then sister, then myself male)
It you are religious, it is up to God who will decide, if you are not
religious, you get what you get.

Maybe these two questions are of interest to you:

http://answers.google.com/answers/threadview?id=381462
http://answers.google.com/answers/threadview?id=444908