Say I tick off the head of my family a great deal and she declares that I no longer am a member of the clan. It’s permanent, irreconcilable and irreversable. I no longer belong to the family. Will the authorities acknowledge this, i.e., when I fill out ‘next of kin’, signing ‘N/A’, or will they chuckle and ask me politely to work it out?
My ex’s uncle basically disowned him, although not through a lawyer. He left him $1 in his will so the case couldn’t be made that he forgot about him. I think legally, a person can put it in their will that they don’t want someone to inherit anything, but they can’t rob you of your genes!
Kalhoun is right: your mother, for example, doesn’t have to leave you anything in her will (and that needs to be spelled out clearly, or you could challenge the will and at least gum up the works, even if your challenge isn’t successful), but legally, your mother is your mother is your mother, whether she likes it or not.
You can be “disowned” to the extent that you are excluded from the wills of your relatives. However, nothing short of a termination of parental rights (which requires judicial approval) while still a minor can sever the parent-child relationship in law. So even if you are written out of the will, you remain an “heir of the body” and if you would be (a) next-of-kin under succession law, you would remain such notwithstanding any declaration of disownment.
If you wish to disown someone, I suggest consulting a lawyer to ensure that it’s done correctly. If you have been disowned and wish to know what your legal status is, again, consult a lawyer. 
I feel like I say what I’m about to say so much in GQ (or maybe I just think it and decide not to bother posting) that I wish it was a sticky entitled “A Note on Requests for Legal Advice” or something like that. (If any mod reads this, I’d be willing to draft up such an OP). Anyway, here goes:
To “disown” someone may or may not have significance under one or more different legal regimes, each with its own set of rules. For example, you mentioned the legal regime governing “who is one’s next of kin” (if there even is one, more on this later) for some unstated purpose, and others have discussed the legal regime governing gifts in wills. Furthermore, each state may have different rules under each of these legal regimes.
Therefore, the question “Is disownment legally recognized?” is a lot like asking the question “How many are there?” or “Which way to Albuqurque?” without saying more-- not only is there not an answer to the question, but there is no way to answer the question without knowing a lot more facts. Even after knowing the facts, I’d have to determine what the state of the law was on the specific legal regime in the specific jurisdiction you care about.
Also, to finish a thought started earlier, sometimes there just aren’t rules that govern something or there is just no way an issue is going to come up. Say you are filling out a form for your employer that asks the identity of your next of kin. Well, what if you are a single and childless only child of two only children, your father and all four grandparents are all dead, and your mother has “disowned” you somehow. Now, say you put your mother as your next of kin. Why would your employer challenge this, and under what body of law would they have a cause of action? Have you committed fraud by lying? What if you don’t put your mother as your next of kin–can your employer sue you to force you to list your mother? Would your employer be so concerned about it’s ability to contact a family member (instead of, say, a friend) in case of emergency that it would sue you over this? You see my point?
Phew! Now don’t make me tell y’all again!
I know this may not be acceptable here, and I’ll only do it this one time (I promise)–>
^^BUMP^^
My understanding of “disown” is what I find in my dictionary–“to refuse to acknowledge as one’s own; repudiate; cast off.” In family dynamics, this generally means not getting spoken to, not being thought of as part of the family anymore, not getting invited to family affairs, being the subject of the cliche “I have no son!” etc. It has symbolic and emotional significance, but is not a legal term.
I think these replies are discussing “disinherit.”
Well, GaryT, I think that in its most common usage, disown is used as a synonym for disinherit, or at least that disinheriting is considered one part of disownment. (It also typically emcompasses cutting the person off from current financial support as well as all communication, both of which are legal as long as the person disowned is no longer a child). You and TaxGuy are certainly correct that a disownment isn’t the same thing as to disinherit someone.
As TaxGuy noted, the legality of disinheriting someone is a matter of state law; in some states you can disinherit your children, and in some you cannot; many states also have a provision protecting a spouse from being disinherited as well.
–Cliffy
Hmmm, I guess it does depend on the law where you live, but I was under the impression that you can leave whatever you have to whoever you want in a will - can give it all to your relatives or to the pan handler on the corner of 12th & main if you say so… unless you leave no will (which is when the courts make your choices for you), no one is entitled to anything, so the concept of “disinheriting” is meaningless as there is no right of inheritance in the first place… it would only relate to removing someone from your will if you re-write it. Obviously things are not like that everywhere though.
I’ve wondered about other such archaic or emotional terms before too, such as forbidding someone to do something (I’ve heard that line from husbands to wives in old radio shows) or banishing a person from your property… are these terms useful for anything more than dramatic effect?
mmmiiikkkeee, many states have established statutes that give the widow (or widower) the right to take a 1/3 (or, sometimes, 1/2) share of the state, disregarding the will. Under the common law, widows were entitled to “curtsy” (basically, support) from the estate and could not be denied that by the will. I think some states have also enacted protections for minor children, but I can’t attest to that as it has been some time since I last looked at this stuff.
Estate law is a fascinating, complex world.
This is only partially relevant, the more so because I live in Hungary where the legal system is different from that of Florida and the situation is probably different also, but it is a case of “disownment” in the legal sense:
My neighbour has (had) an adopted son (now a grown man), who became such a nuisance - demanding money, threatening his adoptive parents, cutting off their electricity, ripping out their TV aerial, etc. - that they literally had the adoption overturned, and he is no longer their son in the legal sense.
Hasn’t stopped him pestering them though…