Being gay or transgender doesn't automatically prevent people having biological children, be that by being in a mixed-sex relationship at some point or by artificial means.So if there is no offspring produced because of being gay, transgender, or whatever...
Also, evolution isn't just about genetics, environment (which includes human society and childhood upbringing) can be relevant too, something anyone is involved in, regardless of whether they have children of their own or not.
Genetics are also not simply binary or direct. Just because an individual has no children of their own doesn't mean all of their genetic elements are lost, since they could still exist and be passed on via other close relations.
No your not. Cis just means your gender identity is the same as you biological sex. It has nothing to do with having children or sexual orientation. The term only exists because saying "not transgender" all the time would be unwieldy. Of course, that label is only relevant or useful in the context of discussions about gender issues. Most of the time it will never be used.But I'm labeled cis for doing all the above.
We're all in the same world. If you want to define "us and them" divisions, you'll inevitably use labels to distinguish them. Every one of us could legitimately have multiple labels applies to us in all sorts of different contexts. The only question is how much you make of them.Honestly speaking from several I know, labeling us is where you lost some support. You can be trans, gay, unidentified, etc... But you dragged us into your world when you labeled us.