If one person is gay in 1 universe and that same person married in another. Then one universe wouldn't have a kid and the other would.
So what the heck, there's no way that you could have the same u because in each universe everyone would be marrying different ppl and producing different children.
No, see, you are viewing it too simplistically. Picture it like this:
Your mom and your dad have you. Your uncle Steve is single, your Aunt Janette is married to a man named Charles (aka. another uncle).
Now in another universe:
Your mom is actually your aunt Jannette from the other universe, and your dad is uncle Charles from the other universe. Your uncle Steve from the other universe is married to your dad from the other universe. And your mom from the other universe is single.
If you take a bunch of people, and rearrange them, you have the same people, just different matches/families/couples/etc. Given, in some universes according to this movie, somebody may not exist, but that is much more complicated to explain, and I don't want to get into it.
Theres a reason why there were only 125 versions of law. Out all he possible worlds, thats the number of laws around. This is the chance of people marrying the corresponding people on another universe. Events and names might be different but theres a chance that everything happens similar enough to have duplicates. So 1 universe can have a life that another universe doesnt have. This is pretty similar to a show called sliders. Infinite worlds with some difference.
yea, there could be a nearly infinite amount of universes that are exactly the same on earth, but have maybe something on the other side of the universe slightly different.