That Y Chromosome
Princess Kiko has had her baby and it is a boy. This will end Japan's facing the possibility of one day having an Empress instead of an Emperor. For 2000 years there has been an Emperor, held to be divine until Hirohito resigned the idea of divinity after the atomic bomb led to surrender in World War II, and an American general ran the country.
All this is against the background of advances in knowledge of DNA and of the nature and mechanisms of life. Eggs have X chromosomes, while sperm have either X or Y, meaning that sex is determined by which brand of sperm gets to join the X egg -- XX gives a female individual and XY a male, so chance determines whether the ruler is divine or not. In many other cultures the same has been true, where only a male could be the boss. It is a flip-of-the-coin matter.
Always, there has been a method of selecting sex of infants, age-old in India and very current in China. This is usually by drowning or suffocating unwanted female babies, although smashing the head end against a wall was often the method when, in the southern American colonies, a white mother had a "tarred" baby.
It is interesting to note that eggs are few, like one a month, while sperm come in the millions, and also interesting that more males are born than females, who make up by living longer -- there are more old women than men.
We are talking sex, and as we consider other species, that becomes very interesting indeed. Some invertebrates, I think among the molluscs, have adults which are male some years and female other years. I'm sure we will get back to discussions of sex again.