Outside of sexual abuse as a child, I really don't know. I'm pretty certain my son is straight and I know I had nothing to do with that. There is so much that goes into sexuality. It's not black and white by any means. Sexuality is fluid and there are very few people walking around that are 100% gay or 100% straight. That's just a fact of us as a species.
I think they have a decent amount of influence (if we're not talking sexual orientation that is).
My parents were very open about sex. I learned early on about the human body, and I never felt ashamed to ask questions. It put me in control of my sexuality, and I was comfortable with who I was at a young age. I did have sex young at 16 the first time. My parents encouraged me to wait, and told me many times the risks of having sex early. But it was because of their open talks that I was well aware of how things worked, and knew how to keep myself safe sexually. I also saw their committed relationship. And I knew that was what I wanted. DH and I were young when we had sex, but we were committed even at that age. We talked a long time about risks and what ifs, and why we wanted to have sex. I"m glad my parents talked openly with me abou sex, because it allowed me to do the same in my relationship. Sure, looking back, DH and I took a big risk in taking our relationshp to a sexual one so early, but I wouldn't change a thing. I have a healthy sexual relationshp because my parents didn't make it out to be taboo or wrong.
I'm with the Majority I don't influence my children to be gay straight bi or whatever. They are born the way God made them regardless of who they love. I didn't randomly choose to be straight I was born Straight (OK more like bent but that's a different story) I love nurture and support my children and in the end they will find love and understanding and I will support them no matter who they love.
as to the sexual abuse statement I was Raped at age 4, again at age 12 and once as an Adult. Along with COUNTLESS counts of sexual Molestation and I can say with 100% certainty that None of that even had an effect on my sexuality but did make me more understanding to others who haven't come through it so well.