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Full disclosure: I am a 21 year old out gay man. This being said you maybe wondering why I am even bothering to answer because obviously my answer is yes (it most definitely is that answer. Whether my son is gay, daughter is lesbian or either is trans I would most definitely support their happiness without a doubt, because in my experience that is a parents biggest duty: to look out for and provide support toward their child in the most effective and efficient way possible.)
I am suspecting my thoughts are probably not what you are looking for by the way you phrased your question; I suspect you are looking for the opinion of straight people who are prepared for this possibility or have dealt with it. That is why I will share with you some words I will never forget, that my Regan worshiping, trickle down economy believing, anti-imagration, consevitive talk show listening, working class republican father said to me at the time I came out:
"I'm glad. We disagree on many things, but you being happy no matter what is one we are in lock step on. I may not understand everything about the gay community, but I understand that no matter what you are my son, someone who is themselves no matter what. So when you get a boyfriend I want too meet him ok?" (Paraphrased)
I apologise for the wall of text, however I hope it was helpful in some way. Thanks for reading it is kinda personal for me :P
Ps: My ex's mom's reaction to him coming out was "I know honey now what do you want for dinner"
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to be honest, i wouldn't just happily say "oh son, you're gay? that's totally cool! didn't surprise me at all!" Because that's not how it's gonna go down. I will question him first if he is serious about it. Because it would definitely surprise me. Even if I do read yaoi, that's different from reality and you can't just brush it off as if you've just entered a yaoi realm. if he comes out and tells me he's gay, I will support, but I will have to make sure first he's honest, sincere, and prepared for what to come and he won't back out if I 100% support him later. My family (parents) is homophobic as hell so I'm all he's got.
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My sister recently came out of the closet and later she went up to me wondering why i took it so calmly. I was just like, "So you're gay, how does that change anything? Don't worry, I'm educated on affairs of the same sex. :)" And went back to reading my yaoi manga.
Now we are both reading killing stalking and hating her ex girlfriends.
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Well for me, since I'm just an adolescent, I know that I would have said yes and accepted him no questions asked. However, if I were to really thing about it, of course I'm going to accept him, but I'll ask him does he really mean that. Does he really mean that and is he determined enough to go through with the consequences that come with being gay? Regardless, I'll accept him because I love him and he's "my future child" (▰˘◡˘▰)
Guys let's be honest. IF you have a son (or more than one) and he's actually gay, will you support him? I think i would, but i don't know about my husband tho. How about you guys?