"One might just as well scream, since the IRS doesn't think my daughter is a qualifying member of my family, "who are those bastards to tell me my daughter is not my daughter???!!!" "

As far as I know the IRS uses the term dependent:
"Qualifying Children
To be claimed as a qualifying child, the person must meet four criteria:

Relationship — the person must be your child, step child, adopted child, foster child, brother or sister, or a descendant of one of these (for example, a grandchild or nephew).

Residence — for more than half the year, the person must have the same residence as you do. (More than half a year means, at minimum, six months and one day.)

Age — the person must be

* under age 19 at the end of the year, or
* under age 24 and a be a full-time student for at least five months out of the year, or
* any age and totally and permanently disabled.

Support — the person did not provide more than half of his or her own support during the year."
http://taxes.about.com/od/dependents/a/Dependents.htm

Obviously being a daughter is not limited by age or where she lives- but a dependent is.