Paula,
Kousa is not a hybrid - though there are some hybrids of it and some of the native American dogwoods(C.florida, C.drummondii, etc.). But, if hers is a straight kousa, the seedlings will be typical of the species, and will be quite similar, in most regards, to the parent tree - floral show may be essentially the same - or it may be less or more showy - but she'll have to wait a number of years for these seedlings to grow through their juvenile period and attain sufficient maturity to begin flowering.
I have some seedling kousas that I grew from seed I collected, and they're probably 7 years old(if not more), with no evidence that they're inclined to begin flowering any time soon.

Thanks lucky p, I was pretty sure of this, but wanted to post here, where I know the advice is good. I have a *probable* straight species kousa myself, with seedlings all over the yard.

luckyp, as an update from years past, your advice to plant a Quercus macrocarpa was indeed sound. I can't believe it's been 5 years already since I planted it, and it's doing well. It has acorns this year! (Is this good, so early, I wasn't expecting them for some years from now?)

Paula,
While you'll frequently see numbers thrown out like, 'Oaks require 35-40 years to begin fruiting', that's not been my experience.
I've had quite a number of bur oak and hybrid oak seedlings begin producing acorns within 5-7 years after transplanting as a 1 or 2-yr seedling - well under 10 years of age, much less that 35-40 mark.

I can't say that I've noticed kousa seedlings popping up around town - but it may be that there are some, but they've not reached maturity to bloom, so one wouldn't necessarily recognize them in the background/understory. I certainly see plenty of the little stony seeds on the mulch surface under mature, bearing trees in the fall when I'm competing with the squirrels & birds for the edible fruits.

thanks Paula and Lucky...I might just pot a few of those baby Kousas and see if they take off...