That's another good point. Something else suggested was that it might be related to how some aren't the same people older that they were younger. Given the intelligence of Digimon, I wouldn't be surprised if that was an influence.

[He's grinning, if you can't tell by his tone.]

Yeah! My brother Martin's Penguinmon, Adele, digivolved for the first time a couple weeks ago, right into Aquilamon.