A lot of the things that "everyone knows" are wrong. The point of science is to have a systematic way to tell the difference between things that seem intuitively true and things that are actually true.
I did a quick search and found a study about percentages of couples raising children [1]. They have a table by couple type and marital status. The difference isn't as stark as you might think.
Looking at the smallest difference in the table, married female/female partnerships have a 30.2% chance of currently raising children, while married male/female partnerships have a 38.7% chance. Is it obvious to you that this would be so close? Would you be surprised if there were countries where the numbers are reversed?
I also doubt that the point of the study was to find out which type of couple had "more" children - even if that is what the news picked up.
It is obviously important for population and demographic research to know just how age, type of couple, divorce, income, etc. effects family size with actual estimates.
I spent a minute looking up the results of existing studies. If a professor at a public university spent a minute to look up an answer for a reporter, I'm ok with that professor having a salary.
I did a quick search and found a study about percentages of couples raising children [1]. They have a table by couple type and marital status. The difference isn't as stark as you might think.
Looking at the smallest difference in the table, married female/female partnerships have a 30.2% chance of currently raising children, while married male/female partnerships have a 38.7% chance. Is it obvious to you that this would be so close? Would you be surprised if there were countries where the numbers are reversed?
[1] https://williamsinstitute.law.ucla.edu/publications/same-sex...