I wonder if you read that statement too literally when it is meant to have a touch of irony- I think JA meant lots of people try to forget their social background by this statement.
But perhaps I am incorrect.
( I bet Lady Middleton didn't bring out the family tree at Barton Park parties- of course, she did have her mother. lol!)

I was abit taken aback by your expression, so thanks for explaining. Sure, go ahead and copy the term of Binglettes, it rather becomes them. ;)