Anyway, I've been toying with some tales of Guy and Tora's future
Tora is probably seriously inbred.
Think about it. Her people have been cut off from the rest of the world for centuries at least, and they forbid mingling with outsiders -- and even if they were more open to mingling, it's not like there are a whole lot of people who are going to brave the Arctic Circle to visit them anyway.
Plus, she's royalty. Look at how inbred the royalty of Europe managed to become, and that was with several families in different countries intermarrying. Tora's people have a seriously limited gene pool to begin with, and I'm sure the royalty doesn't just marry any old commoner! They probably marry into other noble families, most of whom are cousins of theirs, anyway. And they've been doing this for... well, for ages. (Though perhaps it's not as bad if they have a slightly more tribal mentality and marry to the strongest warriors or something? It's hard to say.)
As to whether this would have any effect on her fertility or on the children themselves, well, maybe or maybe not. Though that certainly would be an interesting topic. It seems like whenever something genetic comes up in the comics, it's always some awesome mutation of some sort, but never anything even remotely realistic -- particularly not something that most of us "normal" people deal with later in life. It's never "Gee, mom, I inherited your ice powers, and I'm also diabetic and at high risk for heart disease. Thanks."
Dear Ice People: Guy Gardner is peeing in your gene pool.
And you should thank him.