You could have the question raised in the story itself. How long have the father and emperor been together? Have the android and the girl been raised together, separately, occasionally knowing of the other's existence? Did the two think of each other as 'like brother/sister' at any stage?
So far, I don't believe they ever thought of each other as brother and sister. Unlike others, she did not think of him as just a machine. She can read him well and tell when he has emotions (he tends to hide them).
I agree that you can pull this off without having readers think that incest is a problem, but it's up to you how much of a problem you want it to be, by playing with other factors. Personally, I don't find the fact that he's an android to be particularly indicative; far more important will be the nature of the relationships involved prior to them falling in love. If the emperor and statesman start dating only when their children are independent adults (or android equivalent thereof), then I don't think the question will be problematic at all.
Unless my heroine and the android start saying "Ewww."
Couple of big questions for me and don't take any of this wrong...
What is the genre? Does not sound like teen lit or YA?
Definitely not. I'm hoping to write it as erotic SF romance, but I'm not sure how strong the romantic element will be. (It might be more SF with romance than romance with SF.)
Does the female MC know the other MC is an android? Does her parent know the other MC is an android?
I decided that everyone should know he's an android. Some recognize him as a human (albeit note quite), and others don't. I played with the idea of having the fact that he was an android turn out to be a surprise, but as all these characters know each other, I couldn't think of a way to do this that was logical and not awkward. (Short of his father putting him in a succession of bodies as he "grew up.")
For me, having a human female falling in love with an andriod does not work all that well. I mean, if we are talking love=sex. Why? I know this is going to get me in trouble, but because women are emotional creatures at heart, especially when it comes to the term...love. Sex is seperate from love and I wonder if she can forget during times of intercourse that she is making love to a character that is part machine.
Now if it was just sex, the physical release of pent up urges, then I could accept this as no less than a woman using a sexual aide. With men, most people would not think twice in accepting a male character could bang an android without thinking about the emotions.
I think it will all depend on how you handle the emotional aspects of the human, and in giving the andriod the ability to feel real emotions and not programmed emotions.
This android will have emotions. It may have taken him some time to develop them, or perhaps he had them for longer than anyone else thought, but he hid them. It's possible he had emotions but wasn't sure that was what he had -- perhaps enough people told him he wasn't supposed to have them. I'm not sure yet, but it will be fun finding out.
If you don't know what anger or love is, or what friendship is, would you know you were experiencing them? If other people didn't tell you, maybe you wouldn't understand that right away. Sometimes the things that seem so obvious to us are complicated. When I was a child, my mother would tell me "Go to sleep," and I would wonder if I knew how to fall asleep, and I'd wonder that just before falling asleep.
(OK, my android doesn't sleep, which means he probably spends the late hours reading legal precedent or something. zzz)
See there I go again, allowing my science knowledge, as limited as it is, get in the way of a possible good read... I wonder, did Data ever have sex on Star Trek? If so, was he smiling afterwards? Did he have a smoke?
With Tasha Yar, but I don't know if he smiled afterwards.
While I loved the character, I think they dropped the ball now and then. As the Nitpickers Guide pointed out... He was this incredibly brilliant android, but he couldn't use contractions?
I've always wanted to do this one right.
