This is also not quite right. O is not “recessive”, but it behaves sort of like it is.
Can you explain this assertion? To my knowledge O is a classic recessive allele. It doesn’t express a functional protein, and, thus, is masked by any allele expressing a functional protein, in this case A or B. In addition, there is no partial phenotype. You only test as O if you have two O alleles.
Ask?
Glad to see that you weren’t too bothered by my question, I was worried that it looked too insensitive or nosy and was wishing I could edit or delete it.
From the scientific ideas floated here it seems that it’s not impossible that your brother was a biological sibling. It seems more likely, though, that he’s not a biological sibling. In that case the likeliest scenario is that he was adopted. You would have to ask to find this out, though, or dig around family papers (have you ever seen his birth certificate?) and I can understand your not wanting to ask, whether it’s your mother or another older family member. On the other hand you could raise it with your mother in a neutral, non-confrontational way by just saying that you’re puzzled by the blood types.
Another remote possibility, which comes into play if your mother gave birth at a hospital, is that your brother was switched at birth. (I’m assuming that your mother didn’t give birth in one of the European or 3rd world countries where home births are more common than in the US?) Were you old enough when your brother was born to actually remember your mother being pregnant and going to the hospital? (My own brother was born when I was 8 and I have distinct memories of my mother having morning sickness, almost fainting when we were out shopping, wearing maternity clothes and going into labor. I also remember touching her belly and feeling the baby move inside. So I would find it very hard to believe that my brother was adopted) I know the switched at birth scenario is far-fetched, but if your mother and other family members state that there was no adoption, then given the blood type evidence, which looks reliable and not a mis-type, it could be a possibility.
Are you joking?
Ask your Mother if your brother is adopted.
Joe
I’d be more inclined to believe the “Switched at birth” for a longer time ago, when lawsuits were less of a worry, so procedures were more lax; children in the maternity ward were likely identified by the label on their bassinet than a plastic wrist guard, etc. so an accident was easier.
An obvious question, did your brother LOOK like he was a family member? Most siblings you can look at them and see various family traits to some degree.
There’s also quiet adoption; assuming we’re talking about someone 50 or older, it’s not unusual back then for a child to be adopted by a couple if another family member had a child out of wedlock; and the social attitude of the time would be such that nobody might want to discuss it. I have no idea about the process - when a child is adopted, do they actually change the birth certificate to lie about the parents or do they just put “Mother: PRIVATE INFORMATION” on the new certificate?
What are the odds your parents told him but nobody shared that with the rest of you?
Tell me about it! It seems the very day I’m eligable to donate, the calls and postcards from The Red Cross start flowing in.
Look, ya vampires, I’ll come by and donate when I have the time, ok? I have a busy work schedule. And the one day a week I don’t work, there’s a good chance I’ll be hungover…you really want my hangover blood? I’m guessing no.
~bouv, O-.
(We really get the shaft…oh, sure, you all can take our blood, but when we need some, we have to hope there’s enough of ours left after it was all given away to the people that they didn’t have time to type and crossmatch!)
You’re right, I guess my brain wakes up later than my body does. I’m not sure what I was getting at, and I retract my statement.
It may be moot though - I was reading recently about a process to grow large amounts of blood from stem cells - no donors required!
I used to donate blood, but then I found out that since I’m AB, they almost always just centrifuge it for the plasma and throw the cells away. Nobody wants AB blood.
You should reconsider. Even if they do throw out some of the AB cells donated, AB plasma is like liquid gold. Whenever there’s a big emergency and they don’t have time to type the patient, they give O neg cells and AB plasma. And since in a massive bleed situation, cells and plasma and platelets are given in a 1:1:1 ratio, we need a lot of it!
It’s the B donors that get the shit end of the stick, no one uses much of that.
switched at birth is very possible unless you have a dna sample from him it might be hard to ever know for sure though
Per Occam’s Razor, the simplest answer is that he is a changeling, a goblin child left to replace your actual brother who was stolen away by fairies when he was a baby.
That’s not what I heard.
I’m AB- and when I did donate they sent me a letter that I had Hepatitus so they had to throw my blood out. This concerned me (as I’ve never had it), so I got a full-on blood test and the doctor told me that I had a rare type that gives a false positive with the preliminary tests.
Since thats all the Red Cross uses I cannot take my blood. 
They told me that my type was rare and sought after.
Maybe you were thinking of blue eyes? People use them as an example of recessive genes, but they aren’t.
Quiet adoptions still happened later than that, my mother’s family tends to have a lot of kids young and out of wedlock, one of them was quietly adopted to a married aunt in the late 1970s.
We need your plasma SO BAD. Please don’t stop donating!
Also, not all the cells get thrown away. Some are transfused, especially at bigger medical centers where they are more likely to have type AB patients. Some can be used in research, trying to find better ways to store blood, better anticoagulants, that sort of thing.
Our manufacturing lab used 100 units of AB red cells this week, cells that would have expired and been thrown out. We used them in production of blood grouping reagents, which go out to reference labs across the country who do special typing of blood beyond ABO, for patients with special needs.
I think I was headed down the codominance path with the A and B and then got lost. Lesson learned, no more important SDMB posts for me before 9am.
Man, I’m not even O-, just O+, and eventually I had to start shouting at them to stop bothering me. I donate, sure, but it just got rude - they’d call me at 10 at night! When I asked them to stop they didn’t! Grr!
I used to donate all the time and have O+ blood but they never act like it’s anything special and often times act like they’re doing me a favor by taking my blood
Just a slight hijack: do you all who donate do so at Red Cross? I am O+ and would maybe donate but not to them. I’m sort of curious to know if those of you who had a negative experience (being hounded; being treated like they’re doing you a favor) were at Red Cross.