If the child was part of a woman’s body it would have the same DNA.
Please note that half the time the child is not even the same sex as the mother.
And if ability to live without support is your criteria, well, talk about open the floodgates. The demented, the frail elderly, kids under maybe age 12, the comatose and severely injured the very sick, the diabetic and dialysis patient, — none of them make your cut.
The frail are not part of another human body.