User blog comment:Yunhua98/Quarter Bloods/@comment-3146930-20120322201338

While your above equation would be right while looking at it on paper, there is one problem. As stated in the books (mostly The Son of Neptune), legacies are children of demigods, but they dont always have powers. Meaning the if Percy and Annabeth did have a child, it could be mostly Human with maybe some godly features (like black hair and grey eyes).

There is also the question of how that godly blood would merge if the child did have power. For example, in genetics there are dominant genes which will override other genes (for example, if one parent has brown eyes, the child will most likely have brown eyes regardless of the other parent). So using the Percy and Annabeth example above, the child could end up with sea powers like Percy, but not the smarts that Annabeth has; or they could be very smart, but with little or no control over water.

There is also the possibility that they would have abilities, but not to the same level as their demigod parents. I mean gods are amazingly powerful, but their children are only a fraction as powerful. It could happen with demigod children, so (once again) if Percy and Annabeth had a kid, she/he could be above average in school, and maybe be able to control maybe a handful of water.

Just keep in mind that gods dont have DNA, meaning there is nothing to track genetic wise and there is no guarantee a demigod's child will get any powers at all, or they could be just as powerful as their parent.