Suppose you have a couple - Mr. and Mrs. Smith - and then due to various issues, they need a woman to do the surrogate pregnancy on their behalf instead (we’ll call the surrogate Ms. Doe.)
The zygote that gets implanted in Doe’s uterus would be the Smith’s - and so would only ever have Smith DNA in it - but in which ways would Doe’s body cause the fetus to develop differently than if it had been in Mrs. Smith’s uterus for those nine months?
Presumably, a pregnant woman is putting a lot of her hormones into the fetus, or otherwise imprinting the fetus biologically in some way that would be different than had the fetus been inhabiting some other woman’s uterus all that time. (Things like diet, lifestyle habits, the mother’s health or other attributes might affect it). How would this baby turn out differently by being incubated in Woman A’s uterus vs. in Woman B’s uterus?
Doesn’t seem so hard. Use IFV, induce twinning via embryo bisection, then implant one in the original mother and the other in a surrogate. Repeat a hundred times and see what happens.
Ok, maybe not one hundred percent ethical, but doable in principle.
Those things will of course have some contribution. As one extreme example, fetal alcohol syndrome or other drug use would of course have an impact. But in general, with two women with otherwise similar lifestyles, diet, exercise regimen, toxic exposures, medical history including exposures to viruses, etc., there isn’t any evidence to point to specific different outcomes that one would expect.
