I think the problem stems from two usages of the same word - mother (maybe parent also). Step-mother is the term used to describe that particular relationship (“father’s wife”). It’s just exactly like the step-sibling in groo’s first paragraph I quoted here. Whether you’ve met them or not has nothing to do with it.
OTOH, just because the term ‘step-mother’ is used doesn’t automatically mean that you think of her in terms of being a mother to you. Perhaps we should lobby for a new label. 
This is why I have two moms and two dads. Not legally or colloquially correct, but emotionally correct.
apologies for the slight hijack.
Am just wondering whether it swings the other way round too. I mean is anyone here married to someone who has adult independent offspring? Do you consider them as step sons or step daughters?
Am not in that situation and never likely to be but I can’t see a daughter/son relationship no matter how ‘stepped’ can form if you never had a share in their upbringing. It would seem weird to me.
hijack over
I think the whole subject is weird. Obviously from the OP, I have had issues with my parents, and wasn’t comfortable with the implication that a woman I barely knew could be described by a term with the word “mother” in it. Since for many, it seems more of a categorization than an implicit description of a relationship, I guess I’ll go along with it. I was just weirded out because I’d never thought in those terms before.
Thinking about it some more, my stepmother has done no lasting damage to my psyche, so she’s actually at the top of the list of people described as “parents.”
[hijacking my own thread]
I enjoy reading about President Obama’s complex family relationships. Now we have a president who’s biracial, from a broken home, lived in poverty at one time and became president of the Harvard Law Review. Pretty much my doppelganger (except for that Harvard Law Review part). I’m still mulling over my run for the US presidency in 2012.
[/hijack]
Perzactly.
Groo for prez !!
Wow, weird…by this definition, I have a stepmother, 3 (I think?) step-siblings, and whatever the term is for child of a step-sibling.
Strange to think it would affect security clearance…in that case, I’m pretty much fucked since wife of y-chromo donor is a nutjob.
I have a stepson and stepdaughter; Mr. Kitty and I married when they were nearly-10 and 11 respectively. I had no hand in their raising- actively went out of my way to avoid such a thing, actually, as Mr. Kitty and the ex had things in hand- but 12.5 years later I refer to them as my stepkids for expedience’s sake (“stepson-in-law” is a mouthful, though).
A coworker married her husband when his daughter was grown; she has had fairly consistent contact with her since the wedding (dad was involved throughout the daughter’s childhood, so it wasn’t a case of absenteeism) and uses the term stepdaughter.
I know a twice widowed woman whose second husband had a grown daughter at the time of their marriage. She calls herself step-mother to said daughter ironically when appropriate. She’s not step-mother (or mother) emotionally, but since both are active in one church (and have different last names), it’s useful for clarifiying the relationship for people who don’t know the history. She is considered grandmother to the children of the daughter–which is nice because said grandchildren would otherwise have no living grandparents–but they maintain ties out of affection rather than duty.
Oops! Sorry if I gave you the wrong impression. That wouldn’t prevent your getting a clearance. They’re just looking for unstable behavior, excessive spending, alcoholism, and relationships with people that could be exploited in one way or another. If you had a secret mail-order Russian ^h^h^h^h^h^h^hChinese bride who mainlined crank and gambled excessively, that would be a problem. But I know for an absolute fact that you can have nutjob relatives and still hold a clearance. They just want to know about it.
Fuck, you’re psychic. Stepmom is a mail-order Russian bride who quasi-stalked my bio-mom. Yes, really.