Care Bears Family Adventures: Book 1, Chapter 6
While the care bears and care bear cousins had aged to adulthood in less than a single year they were still naïve and dark heart had been able to capture all of them while his shadow led noble heart, true heart, sage heart and grams bear on a wild goose chase
Care Bears Family Adventures, Book 4: Chapter 10
"noble heart was born in 1981 and from what he's told me he was transformed from a normal horse into a care bear cousin the night he was born; from what little we know about the catalyst crystal that created us we know that he, true heart, grams bear, sage
Care Bears Family Adventures: Book 2, Chapter 1
Discussed but easily noticed is that care bears and care bear cousins stopped aging once they reached the rough physical peak of their lives, at physical age 25 to 30; a side effect was that they were literally "only as old as they felt" in fact when grams bears