I find human sexuality to be a very interesting topic and I can be very open about it with the right people. There's a select few who I am more open with the anybody else who I am happy to talk to about my likes/dislikes etc and pretty much everybody (although some far more than others) is very open with me (seriously, like 7-8 people have come out to me so far).
I love it when people talk to me about sex and sexuality, it is one of the most surprising, interesting, in-depth and personal areas of conversation there is and I love that because I love learning how people think.
As far as being open about sexuality with my eventual kids, I'll be open enough that they'll know about different sexualities, know where babies come from, know to be careful and know that they can come to me for anything (like any kid in the history of ever has gone to their parents to talk about sex willingly). More than that, I'll be happy to answer any questions but it is up to them to ask said questions if they want my answers, I won't randomly blurt out these things.
I never got the talk growing up (thank God), and I never really needed it. I learned the biological side of sex from documentaries and school and the like and learned about sexuality through life (with a few little bits from our crappy sex-ed system) and that way I formed my own sexual identity without too much influence from other sources and developed my own ideals about sex and sexuality. We're pretty open about sex/sexuality in my house these days, but that is mostly just humour (yes, I make sex jokes with my family) but I know full well that we'd have no problems with more serious conversations if they were ever needed.