A couple of points have occurred to me.
My parents had 6 children, who in their turn had 11.
Those 11 have now produced 10 of my grandchildren's generation. I feel very confident that my children won't produce any more grandchildren (we have 2). All bar 1 of my children's generation are now over 30, and three of them are over 40.
That represents a small decline in the population.
My father was an only son, but had 4 sisters. The Walker surname is well-represented in my generation and there are 6 males in the next whose surname is Walker, but our grandchildren's generation have no boys with the surname Walker. I think we are an endangered species - our bit of it, anyway.