Another argument for justifying the expansion of marriage to same-sex couples addressed by ‘Discussing Marriage‘ regards supposed research showing that there is no difference in the well-being of children raised by a same-sex couple than that of children raised in other family arrangements. The argument would go something like this:
P1: Research shows no difference in the well-being of children raised by a same-sex couple and children raised in other family arrangements.
P2: Children will not be harmed by being raised by a same-sex couple
C1: Same-sex marriage should be legalized
The web site linked above calls this argument something of a red-herring. The well-being of children is not a primary argument that is used to oppose same-sex marriage. The response also includes that the bulk of historical research has shown that children are better off being raised by their own biological parents than in any other arrangement. The authors of the site are critical of some recent research because of small sample sizes, lack of random sampling, cultural bias and other factors.
For more details and references I would refer you to the Discussing Marriage website.
Eric Nielson
Small and Simple 
“The well-being of children is not a primary argument that is used to oppose same-sex marriage.”
I agree to an extent- this argument is used by opponents, but not too frequently (although it was used int he supreme court just a few days ago- “When you change the definition of marriage to delink the idea that we’re binding children with their biological mom and dad, that has consequences” said attorney general John J Bursch).
Either way, it’s irrelevant, since marriage is regulated by the government and child-bearing/rearing is thankfully not. Oppose same-sex marriage all you want, but homosexuals can still have children (adopted or otherwise)- that’s not legally up for debate. And if they’re going to have children (we can’t stop them, short of sterilizing them), the evidence suggests that outcomes are better when the parents are married.
“The response also includes that the bulk of historical research has shown that children are better off being raised by their own biological parents than in any other arrangement.”
Whether or not that is true (and empirically supported) is beside the point. Legally, we leave space for many non-biological parenting situations (and the marriages that may or may not be part of the arrangement. Even if 90% of biologically-raised children ended up perfect and happy, and 90% of children raised by non-hetero-normative parents ended up miserable- who’s going to be the judge that denies the other 10% the chance to be married parents? And who wants to explain why the 10% of crappy heteronormative parents get to be married but the 10% of awesome gay parents don’t? Obviously my 10/90 statistics are completely made up, but the point remains- statistics don’t matter when you are looking at an individual who wants the same opportunities as anyone else.
You make some good points here. Thanks for the comment. I am against the legalization of same-sex marriage, but I am actually not greatly passionate about it. Somewhat similar to what you have stated, homosexuals are going to love, cohabitate and have sex with whoever they please regardless of what is made legal. So to me the question is how far ought government go in regulation of relationships? I would tend to say not very far. For me heterosexual marriage with its higher frequency and expectation of childbearing and raising passes my threshold for adequate justification for regulation where other relationships do not.