Being the grownup

Who is the grownup when you get old? That is the question I'd liked answered. I find as I age that I take on more the role of "wise elder" to younger colleagues, but who do I get to have as an advisor? I'm still young enough that there are people older than me, but at some point I'll reach the end (front?) of the line, right? My younger siblings turn to me for advice and counsel, to some extent I turn to my older sisters, but who does the oldest get to have as a mother stand-in?