Why to be shy of having kids grown-up?

While advancing in years and having kids growing up the same time, some women make desperate and ridiculous attempts to disguise their parental relation to those kids and out of sudden, instead of daughters and sons, they aquire "sisters" and ... no no no - no "brothers", but "boyfriends" (BTW is something Freudian in there?).
And they make kids to follow this pattern and avoide "Mum" when in public and - I've seen it - even at home.
Never understood that.
Our daughter is a mature teen and a child of young parents. She's taller than me, bigger than me (I'm not a good measurement unit anyway), beautiful and serious-looking girl, with all that make-up and trendy attire. Very often people from work, new friends, her schoolmates and just guys from the street do not beleive that I'm her mum. But I never failed to point out that Ksusha is my daughter and I'm proud of it.
And I'm not shy when she calls me Mum and people turn heads and make surprised faces.
Because being a mum (and I beleive, a dad as well) - it's happiness.
Caring about children, sharing their thoughts and problems (the latter may be as great as a Universe!), having fun with them and even when they make fun of you - all this makes you young and drives your life on a high gear, so that you won't fall under temptation to observe the world and reflect on the future of humanity.
Yes, "caring" and "sharing" might be such a burden sometimes! But look on the bright side: having a grown-up son(s) or daughter(s) and remaining still young, dynamic and with a whole world open for you for discoveries - isn't it an achievement? Why to be shy of it?

P.S. I'm not talking about the age, of course. Everybody knows that disclosure of the woman's age is a crime! Just advocating mother(father) hood...