What blood types make R-?

[Davros]

I need to find out which blood types parents of a child with Rhesus Negative would have? This is to try to narrow down who may be the biological parent discreetly

you can't narrow down blood types for Rh- as it's a dominant gene so someone who is Rh+ may carry one gene for -ve and one for +ve.

www.rhnegativeregistry.com/rh-negative-factor-recessive-trait.html

Thanks for the info and link. I am finding it all quite impenetrable but here is some extra info:
Child is Orh negative
One parent is Orh positive
Is it possible to narrow down what blood type(s) the other parent would have to be?

The other parent needs to be O-ve (though there are some very unusual blood groups/combinations that can give current results, so there is a tiny chance otherwise)

They would need to be o as that is recessive but could be rh + or - as explained above. Why so cloak and dagger

One parent believes they are the biological parent but may not be. So I am looking for ways to find out without giving the game away. I also need to find out if a DNA test can be done without the knowledge of one parent. I doubt it.
Thanks for your help

The other parent could be any type I think. Look in link at brightly colour table in genetics section

en.wikipedia.org/wiki/ABO_blood_group_system

the pale red, pale blue and pale purple combinations could be O blood despite one parent being A or B (but not AB)

I'm O neg and my older son is too. My husband is A.

I'm pretty sure you need to get consent for DNA.

Actually yes o is recessive so anything other than ab could be the parent..

I don't think the other parent can be AB, but a parent with A,B or O blood could make an O child.
RH status could be either.

Thanks. I expect permission is required for a DNA test but that would mean huge upset and the "unaware" parent could turn out to be the biological parent anyway. Tricky

I am curios about this, tried to read up on it but its quite mindboggling!

I am A positive, one of my children is A positive but the other is A negative. We dont know what my husband is and have wondered if he had to be negative to have the A neg child? But not sure

Hyacinth, we each have 2 copies of our blood type. (1 from each parent)
With the Rhesus factor, if you have it from either parent, you are rh+.
Since you know that one of your children is negative, and you are positive, you must have Rh+/Rh-

You have passed your Rh- to your negative child, and they must have also got a Rh- from your DH.
You have passed your Rh+ to your other child, and they either have Rh- or Rh+ from your DH.
Your DH could be either Rh+/Rh- (and therefore Rhesus positive) or Rh-/Rh- (and therefore Rhesus negative.)

Does that make sense now or have I just confused you further?!

Davros, are you one of the parents?

Somerville, thank you, thats a very clear explanation, i understand it a bit better now!

Oh good.

I've explained it in RL with sweets and pieces of paper saying this-is-not-a-sweet and was just working out if I could do it with !

If 1 parent gives you a and the other gives you something saying not-a-biscuit then you have a biscuit.
You can give your child the or the not-a-biscuit.
Etc...!

No, I am not I e if the parents (thank god!) but it is someone very close to me who is distraught and I want to help emotionally and practically