When discussing whether Homosexuality is morally right or morally wrong, I've always argued that if we allow homosexuality then we would have to allow incest as well. Before arriving to this conclusion I first looked at the various arguments defending homosexuality which mainly consisted of the following: 1) It's consensual (with the exception of rape); 2) It doesn't harm anyone; and 3) It's a matter of love (i.e., we should have the right to be with whomever we love). Now my reasoning is this: All three of those arguments could be used to defend incest! Imagine a father who becomes sexually involved with his 20-year old daughter. Both would be consenting, they are not harming anyone, and they presumably have some type of attraction towards each other. My question is if my argument is a good one or am I missing something?