So you do not want your son to grow up and be a father and have a family? I doubt your honesty. If your son does become gay, you will look back on his past life and upbring and search to see if it was due to some thing you did or your fault in the way you raised him. Again I doubt your honesty.
I have a son, so this is not a hypothetical question for me.
Yes, I would like my son to be a father and to have a family, but biologically fathering a child with a woman while in a heterosexual relationship is not the only way one can be a father. Adoption is only one of the ways one can become a father, and to me it's a win-win for the child and for the family who chooses to bring that child into their homes. There are plenty of family situations that are worse than two responsible, caring men taking care of and raising a child.
I can tell you with 100% certainty that I will never look back and wonder what I did to "make him gay" shall he be so. If he flunks out of college, does too many drugs, knocks up a woman and doesn't act like a father, is abusive, goes to prison,and many other things I'll fret and wonder what I did wrong.
But let me tell you this and tell you this clearly: I don't give a rat's asshole if my son turns out to be gay. Zero. I simply don't care if he's straight or gay. I care that he has fulfilling, healthy relationships and is happy. Period.
Regardless, as everyone else has said, gay isn't a disease you catch from other gay people. DUH.