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?

[1] https://williamsinstitute.law.ucla.edu/publications/same-sex...