Every few years I go to a family reunion on my Mom's side - descendents of the first matriarch and patriarch who immigrated from Europe to this country. There are HUNDREDS of us, most of whom I don't know at all or barely know. Meeting many of these relations for the first time is a bit dull and no different from meeting a new acquaintance in any other manner.
Why do I go? Because I am OVERJOYED to see cousins, aunts and uncles I bonded with when I was a kid. It is amazing reconnecting with loved ones, even if it is years between visits.
I also notice that my little step-daughters really love my niece and nephew, their "cousins" who are actually not related at all (two sets of twins - so adorable!) They say cute things like, "My counsins' birthday is a very special occasion so I would like to help bake the cake." I can already see these bonds lasting a lifetime, long after we grownups are all gone.
We can't predict how DE kids will feel about blood relatievs. All this to say, chances are that what matters most is where the bonds are.