And it may be a fine point, but we do not say Christ is present IN the “wafer” after the consecration. Rather, there is no more “wafer”. What is on the altar is 100% Christ and nothing else—the substance of the “wafer” is annihilated entirely and only its accidental characteristics remain.
THis does not seem to be an answer. This just explains what is done during the Eucharist. 100% Christ is 50% Mary.
Well, actually, maybe not, because where would His other 50% come from? There was no human male involved.
But at any rate, we are not just bodies but body-soul combinations, so whatever Mary contributed to the body of Christ, His human soul and divinity certainly did not come from her.