The census already asks about your sex. If you want your descendents to know if you are LGBTQ you should tell them. This is unnecessary. You don't want your employer to have the ability to hire or fire based on orientation but you want other countries to know? I'm a genealogist and people from other countries researching their ancestry or working on literary works view census data. Your orientation doesn't make the research information any more or less helpful. If you want the world to know you're female but a lesbian write your biography.