Try telling it to Mary, Pete, John, Tom and Dave

Those are my siblings, all younger. I'm guessing they may react differently to this item than I did:

WASHINGTON (AP) - Boys at the top of the pecking order - either
by birth or because their older siblings died - score higher on IQ
tests than their younger brothers.

The question of whether firstborn and only children are really
smarter than those who come along later has been hotly debated for
more than a century.

Norwegian researchers now report that it isn't a matter of being
born first, but growing up the senior child, that seems to result
in the higher IQ scores.