What is a man?

I've been turning it over and over in my head. What's the point of limiting this right?
Now we'll need legal definitions of man and woman. Does a man have to have individual, well formed X and Y chromosomes? Does an XXY male qualify legally as a man? Does a woman have to have two well formed X chromosomes? What if they've got the right chromosomes, but have otherwise been physically altered in another way? What if a "man" has no testes? What if he has no penis?
Do the pair have to be able to copulate? Do they both have to be fertile?
What's the legal gender of a transgender individual?
Are we making a legal distinction between man and woman with boy and girl? Do they have to be "of age" both mentally and physically? Is a "man" a qualifying participant if he's 21 but has the mental capacity of an 11-year old? Is a male a man as soon as he produces viable sperm?
What if a "man" or "woman" loses one of his or her qualifying attributes after marriage? Does the marriage get annulled?
Why does California want this in its constitution? What good could it possibly do?