If it's about in utero magic exposure, even a purely mortal mother who spends a lot of time around a very powerful wizard would probably be enough to do it.
The upshot of what we've been told, and what's revealed in the books, is that magic is partly a genetically inherited trait, and partly a learned skill, and partly something else, all interacting together.
The genetic component can be inherited from either parent like most others, but whether that genetic potential will ever
manifest itself depends to a considerable degree on environmental factors, again like many other inherited traits. You can inherit a genetic predisposition toward getting addicted to a given drug, for ex, or catching a particular disease, but if you never encounter that drug or are never exposed to that pathogen, it won't matter and the effect won't happen. You can inherit the genetic potential for better than 20/20 vision, but if something external damages your eyes, you may still be nearsighted.
You can inherit the magic potential from either parent, but it's a lot, a
lot, more likely to manifest itself if you're exposed to magic a lot in the formative stages. Which means the child of a magical mother is more likely to be magical than the offspring of a magical father, everything else being equal, because he or she is exposed to that magical activity during 9 months of pregnancy. But as noted by peregrine, if dad is magical and mom is not, but dad is right there all the time slinging magic for some reason, it might improve the odds a lot.
But even then, it also depends on training and unknown factors too. Harry and Molly, or Harry and Elaine, might have a kid, and that kid is getting high-power magic genes on both sides. But if he never bothers to train and decides to spend his time becoming, say, an airline pilot or corporate lawyer, he'll never be a Council Wizard even though he almost certainly had the potential.
Magic also involves both the body and the soul. For ex, when Luccio is transplanted to a new body, she still has all her skill and knowledge, she's still Wizard-level, but there are things she can't do as well because the other body has different potentials. How the soul-side of it rises and passes on we don't really know.