Why do some people refer to their sibling that has a different Mom/Dad as half brother/sister? Come on, why can't they just say my brother/sister?

I've even heard that if you have the same Mom that you are whole because you are blood siblings, but if you have the same Dad but different Moms, that you are half siblings.

Anyone know what is correct on this?

My view on this is that if you have one of the same parents that you are whole. Forget the half, even tho literally, you might be.

Brothers and/or sisters are children of the same two parents. If the two siblings share only one parent, they are half brothers and or half sisters. For the sake of accuracy that is how they are defined genealogically and accurately. Of course, any individual set of half-siblings are free to refer to one another as they choose, and it could well indicate how much or how little love there is between them. The same would be true of adopted siblings, I suppose. With divorce and 2nd marriages being as prevalent as it is in this country, half brothers and sisters are rapidly becoming quite common. And whether or not you share a mother OR a father is irrelevant in the eyes of the law.

My Dad has two younger half brothers. As far as I know, he refers to them as his brothers. Just not real brothers.

I have 2 sisters I grew up with, and one brother (same dad, different mom). I refer to my brother as my half brother, more because I hardly know him. DNA-wise, we are siblings, but relationship wise, I have seen him once since he was 4. It doesn't seem right to include him in the same phrase with my two sisters that I share the same parents with because we are all so close.

If the situation were reversed, and my (half) brother and I grew up in the same house, it would be different for me, and I would call him my brother. I am sure my step sister (don't share either parent, her mom is my step mom, but she lives with my half brother...confusing huh?) calls him her brother, even though they don't share parents at all.

My dad was married before he met my mum. He had two daughters from his previous marriage. I have never met these women who are by now at least in their late 50's. Why should I refer to them as my 'sisters'? My brothers and sister are the ones I have grown up with, not these two. They have not and never will be any part of my family.

It has a LOT to do with your relationship. Families blend by having solid relationships. I think the title of father, mother, brother or sister is earned and not just given. You can have a sister or brother by marriage, through your parents or the families of your parents. I think a family is a mixture what you put into it and what you get out of it. I know some people who have biological sisters and brothers yet they are not even recognized as being family. (Sometimes a stranger is better than your own blood) It is all about the relationship. Sharing one parent makes you 1/2 siblings regardless of which parent it is. (genetically speaking)It does seem like the younger you are when the families blend, the more likely you are to refer to a 1/2 or step sibling as your "brother" or "sister". It is a matter of what you feel in your heart.

Cool! I agree with all of this!

My brother, sister and I all shared the same mother, but all had different fathers. We were brother and sisters. Period.
They had "half-siblings" whom they didn't even know, raised by their Dads.
Bears out all that's been said.

I had a "step-sister": L lived with my step-mother and called her "Mom." No adoption. (L was already grown when they met.) I have always thought of L's daughter as my niece.

Now - my husband has a "half-brother" and a "half-sister" whom he "half-claims."
Weren't raised together. When he claims them, they're his "brother" and "sister."
(But if he doesn't claim them, he gets to be oldest! )

BTW - M-W defines "sibling" as: "one of two or more individuals having one common parent"
(Similar definition from Webster's Collegiate Dictionary.)
Doesn't mention "half."

And my dad spent quite a bit of time away from his half-brothers actually. They lived in Arizona for awhile with the mom they shared with my dad and my dad and his 2 real brothers stayed with other family. I'm not sure how they came so close. Maybe they grew together after college.

I agree with everything said here. We're right now working on a family geneaology for my husband's family, and there are a number of adoptions and remarriages. For him, even though his mother remarried when he was 10, he calls his stepfather his dad (but calls him by his first name to him). He refers to his biological father only by his name, rarely as "my father", never "dad". His half sister is just his sister, and his adopted sister is just his sister, even though he's not close with the adopted one, but his half sister is. His adopted aunt's kids are his cousins, as is the child of his uncle's second wife from her first marriage. I agree, its all on how you look at them.

Getting along with half brothers or sisters has nothing to do with relationships whether you or close or not. We have nothing to do with who our parents are or who our sisters and brothers are. Titles of brother, sister, mother or father is not earned. It was already predestined. Everybody seems to want to put God out of our creation. Well, it cannot be done. I'm tired of hearing people talk about mother nature and the man upstairs, We need to ask God how we can Love our sisters and our brothers whether we are related or not, how to love our fellowman each day, especially how to love the ones we hate or don't like. I am 1 of 11 brothers and sisters the 2 oldest have a different father. We have always considered them our brother and sister because we came from the same womb. Now, after having so many brothers and sisters I never will understand why I am the most hated, but God is helping me to cope with it. I was thrown out of the house like yesterday's garbage. Everybody has a place to live except me. I gave up my home to stay with my mom who is 83 yrs. old, but I have never felt like I was a part of her and my dad sexually molested me so I hope this helps someone because God let me know that when mother/father forsake you he will take you up and these were my biological parents and sisters and brothers.