That's a good link since it linked to the actual study.
https://www.sciencedirect.com/science/article/pii/S0049089X12000610
The biggest issue I've found with the study is that it doesn't seem to differentiate between planned and unplanned same sex families. The study is about adult children of people who have had a same sex relationship. It doesn't seem to be about children raised in a household with two same sex parents that would consider themselves to be married. The latter part of that statement is impossible, anyway, given the scope of the study, dealing with adult children who grew up when gay marriage was obviously not allowed. It seems the study includes children who grew up in a household with a mother and father, to which one of them had an outside relationship with someone of the same sex. I really wish they would have made that differentiation, or was more distinct about it.
In any case, from the study itself:
(section 1.3, paragraph 2)
There are other things I'd discuss about the study, but I don't think it'd be taken in the context I would intend them to be in.