They still have a mom and dad, not a mom and mom. In fact what are the demographics of same sex relationships compared to normal relationships?
I think you need to ask a different questions:
How many have a mom and dad (really present)
How many have just a mom
How many have just a dad
How many have two moms
How many have two dads
I am not trying to be a lib here. Look at my other posts.
I work for three people:
A single man (no kids - straight, divorced)
A mom with dad (beautiful baby boy)
A dad with dad (yup - 2 men with a beautiful baby girl)
I think you're going to see a generational change here. There are too many people who are encountering these events.