Human embryos are not people with rights or moral value

Personhood requires at the very least the capacity for developing consciousness, which is not possible until the 24th week of gestation, at which point >99% of abortions have already occurred.

Conception cannot define personhood, since identical twins form from a single conception yet are distinct people, and chimeras form from multiple conceptions yet are a single person. Brains are what determine personhood, not genes, or conception, or even bodies (conjoined twins are different people sharing a single body from a single conception).