yes it is. I once took great care of it, never let its happy or hungry go down at least 2,50 pounds, never had 2 or more messes on the screen, and I got an oyajitchi. I quote, "It's completley normal."
You know, I don't really think it matters. It really doesnt matter whether it's a reble or not, what really matters is if you love it! Personally, Hinotamatchi is my favorite teen character ever! Just enjoy your tama, don't fret about what character it is! My brother has Hinotamatchi, and he doesn't mind, so......
I took great care of mine and got the one that looks like a maid...then finally forgot about it for a day, then paused it for a day or two and got a mimitchi...so who knows. LMAO
The toddler you get is completely random... with a tiny bit of the care factor involved. The teen tells a little more about how well you took care of it, and the adult seems to be the most clear about how well you took care of it. You might get a "good" character when your Tama grows up... I have gotten Mimitchis and Mametchis with rebels, so don't worry! Hope that helps!