Check the lease and check local ordinances. There may not be a state-wide law on this, but sometimes local towns will have regulations on apartments, or the lease may specifically state the maximum number of residents.

Two adults and 4 kids, my guess is the neighbors didn't just randomly move in extra kids.

I always heard here in Florida that it is 2 people per bedroom, so a 2 bedroom unit should house 4 people, 3 bedrooms = 6 people, etc.

I did a google.com search using the words "Texas rental laws +occupancy" and found this. You might want to search with the same words and see other sites.

Here is a link that might be useful: Texas occupancy limits

I wish houses had the same occupancy laws. I can't tell you how many times applicants have tried to cram as many as 6 adults in a small 2 BR house. No sleeping permitted in basement, no legal fire escape. Some even go so far as to argue with me, and ask "who am I to dictate that". Sheesh. Our local ordinance, as far as houses, is owner's discretion.

I think it's not allowed but who cares

Call your county code enforcement department and ask.

I know of a place in Connecticut where they have 4 adults and 2 kids crammed into a 2-bedroom apartment.

this is why I rent in complexes that only have studios and one bedrooms with college students... people trying to cram 6 into a 2 bedroom would be hell with all the people around them.. there'd be noise almost around the clock.

Where I am in FL it is 2 adults per room but my upstairs neighbors have 5 adults and 2 children under 5.