I'm a US citizen, but have lived abroad my entire life. How would I even start on name or gender marker changes, I know nothing about how this works in the US! I was born in Cali. Thanks.

I don't know but to start you would have to contact your birth state and find out what they require. If you are in the states, you take the same step and then use the court system in your current state to provide the documentation required by your birth state. States have different requirements so there is no standard rule on this.

Thanks Dena. I actually live in the UK. I think I'll try the embassy here first. I'm hoping I'd not have to travel to the US to make such changes.

Google may save you a trip to the embassy because this isn't done on a federal level. It's done within the state or between states. As I was born in Wisconsin, I need to get a name change court order in Arizona, bundle it with my gender change paperwork and ship it off to Wisconsin. As you are out of the country, I am not sure if the court of your birth state will recognize an out of the country court but they may have a procedure in place for such cases. The rules are different from state to state so look up the state requirement first. It's all on line and a google of "state birth records" should get you to the correct site.