First, I'll say that I'm not here to argue or to prove myself write and you wrong. I wish only to illustrate the sheer complexity of these issues, and how they can almost never be reduced to a "true or false," statement of fact. In biology, we take an "it depends," approach instead.
The rhesus factor (Rh factor) was named after the experimental subjects in which it was first identified, the monkey of the genus Rhesus (not an ape, like us). It was later found to present in some humans as well. Not that we inherited this trait from monkeys, but that both humans and the monkeys inherited this trait from the same, now long extinct, common ancestor.
The Rh factor is what we call a dominant phenotypic trait. This means one only needs a single working copy of the gene to have Rh+ blood. Humans have two copies of the chromosome, and potentially two copies of every gene. This means that everyone has either two functionally expressive Rh+ genes, two Rh- genes, or one of each. We inherit only one chromosomal body from each of our parents, with each parent passing on only half of a randomly determined set of genes. If you have two parents that are heterozygous (each of them has both one Rh+, and one Rh- each) both parents will have Rh+ blood. Due to dominance of the Rh+, and the fact that both parents also carried an Rh- allele, it is probable that 75% of their children will be Rh+, and 25% of them will be Rh-. This is the same phenomenon that accounts for two brown eyed parents to have a blue eyed baby.
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