NJ, PA, or MA can't be compared to Texas or California. MA and NJ are dense, and have high populations for their landsize, but have never really been bigger than CA or TX, unless you consider year <1900. Even in 1900, Texas was bigger than NJ, although MA was bigger, but TX and CA quickly grew in the years to come, quickly eclipsing those states. Not due to all being illegals.
Now if we are talking about the birthrate of illegals vs legal Americans, its like comparing rabbits to pandas. AND yes, having too many kids is being selfish, especially when a lot of them can't afford it and thus carry out the burden to all of us.