While biology is science, it is certainly not finite. We're discovering more and more about the human mind and body every single day. Even scientists' findings that would span decades old have changed. Anything can, and will change. Family is not biology. Never was, never will be.
There is no so-called agenda. There is no conspiracy. You seem to be the one who is sexualizing LGBT and painting it as bad, when heteros have been doing the same type of things for centuries. People turn a blind eye to it, because it's become the societal standard. Once that standard is challenged, those who don't question the standard are up in arms and think they are being attacked. Many worry about something that is being taken away from them (family, marriage, etc.) that doesn't affect anyone or anything in the long run.
This goes to everyone: You (or no one else) gets to decide what "family" means to anyone not even your actual family. If you feel family is a man, woman, 2 kids, cat, dog, white picket fence, and so on, then so be it. Just don't expect anyone outside of you, or even in your family themselves to follow the same thoughts as you personally. We are all individuals. We make decisions that help enrich our lives. Happiness is the key here.