threelittlebirds"]I've heard of cases where a man can produce more of one sex than another, but everything I read says it's a 50/50 split each time.[/quote]
It is definitely a 50/50 split. In a clinical study by MicroSort, every man tested had 50/50 ratio of X and Y sperm -- and these were men who had fathered at least 3 children of only one gender.
Can DH's sperm be tested to make sure he is producing both X and Ys.
You could, but it would be quite expensive. He is making X's and Y's. :-)