Unsolicited circumcision advice - yikes!

Melissa • Just tracking my period!
This is purely a "vent" post. My two (gay) uncles lectured me and my SO for 20 minutes about how, if we choose to circumcise our son, we are "mutulating" him. They went on and on about gay men and foreskin, how it's a "free country" and, as such, we should give our kid the option when he's older....They gave us a brochure about "infant mutilation" that they got from an artist they met who was painting with his foreskin!  (I live in San Francisco--this isn't that weird, haha!)
I was so offended (not entirely by their opinion, but more that they were giving it completely unprompted) that I didn't say a word. Now I'm just stewing. And I'm really afraid it's going to come up again too. 
(Meanwhile, my father in law keeps telling us anout how we need to baptize him or he will go to hell.)
 My SO's family obviously thinks child-rearing is a democracy. 
Any ideas about what I can say to make this stop? I don't want to get too defensive, particularly because I'm so mad at this point. 
P.s. We decided on circumcision, and I'm not sharing this with the family. It's private, and I'm not opening it to debate. Not baptizing either. Sheesh.