Why would a parent, who loves their child, and wants them to grow up healthy, well adjusted, 'normal', work to repress something that's totally normal and natural? It's going to happen whether the parent likes it or not, why wouldn't you do all you can to teach your child that it's a wonderful thing?
If they're doing even a half decent job, they should have ZERO influence over their child's sexuality.
If they're influencing it in any way, they're failing big time. Other than working to repress their kid's sexuality, I can't imagine what other influence they coul have.
My first son is openly heterosexual. My second son is too young to express his sexuality so I can't assume anything. I don't believe I've contributed anything to their sexuality other than helping them to understand it. As far as their gender is concerned, I was only able to contribute the x chromosome so not even their gender was up to me.
I'm way more concerned with both of them finding a person they love and who loves them back, the gender is unimportant to me.